English clause syntax
Types of clause 
Clauses can be classified as independent (main clauses) and dependent (subordinate clauses). A typical sentence consists of one independent clause, possibly augmented by one or more dependent clauses.
In interrogative main clauses, unless the subject is or contains the interrogative word, the verb precedes the subject: Are you hungry? Where am I? (but Who did this?, without inversion, since the interrogative who is itself the subject). However such inversion is only possible with an auxiliary or copular verb; if no such verb would otherwise be present, do-support is used.
In most imperative clauses the subject is absent: Eat your dinner! However imperative clauses may include the subject for emphasis: You eat your dinner!. The form of the verb is the base form of the verb, such as eat, write, be. Modal verbs do not have imperative forms. Negation uses do-support, even if the verb is be; see Negation below. The imperative here refers to second-person forms; constructions for other persons may be formed periphrastically, e.g. Let's (let us) go; Let them eat cake.
A dependent clause may be finite (based on a finite verb, as independent clauses are), or non-finite (based on a verb in the form of an infinitive or participle). Particular types of dependent clause include relative clauses, content clauses and adverbial clauses.
In certain instances, clauses use a verb conjugated in the subjunctive mood; see English subjunctive.
Clauses can be nested within each other, sometimes up to several levels. For example, the sentence I know the woman who says she saw your son drinking beer contains a non-finite clause (drinking beer) within a content clause (she saw your son drinking beer) within a relative clause (who says she saw your son drinking beer) within an independent declarative clause (the whole sentence).
Non-finite clauses 
A non-finite clause is one in which the main verb is in a non-finite form, namely an infinitive, past participle, or -ing form (present participle or gerund); for how these forms are made, see English verbs. (Such a clause may also be referred to as an infinitive phrase, participial phrase, etc.)
The internal syntax of a non-finite clause is generally similar to that of a finite clause, except that there is usually no subject (and in some cases a missing complement; see below). The following types exist:
- bare infinitive clause, such as go to the party in the sentence let her go to the party.
- to-infinitive clause, such as to go to the party. Although there is no subject in such a clause, the performer of the action can (in some contexts) be expressed with a preceding prepositional phrase using for: It would be a good idea for her to go to the party. The possibility of placing adjuncts between the to and the verb in such constructions has been the subject of dispute among prescriptive grammarians; see split infinitive.
- past participial clause (active type), such as made a cake and seen to it. This is used in forming perfect constructions (see below), as in he has made a cake; I had seen to it.
- present participial clause, such as being in good health. When such a clause is used as an adjunct to a main clause, its subject is understood to be the same as that of the main clause; when this is not the case, a subject can be included in the participial clause: The king being in good health, his physician was able to take a few days' rest.
- gerund clause. This has the same form as the above, but serves as a noun rather than an adjective or adverb. The pre-appending of a subject in this case (as in I don't like you drinking, rather than the arguably more correct ...your drinking) is criticized by some prescriptive grammarians – see Fused participle.
In certain uses, a non-finite clause contains a missing (zero) item – this may be an object or complement of the verb, or the complement of a preposition within the clause (leaving the preposition "stranded"). Examples of uses of such "passive" non-finite clauses are given below:
- to-infinitive clauses – this is easy to use (zero object of use); he is the man to talk to (zero complement of preposition to).
- past participial clauses – as used in forming passive voice constructions (the cake was made, with zero object of made), and in some other uses, such as I want to get it seen to (zero complement of to). In many such cases the performer of the action can be expressed using a prepositional phrase with by, as in the cake was made by Alan.
- gerund clauses – particularly after want and need, as in Your car wants/needs cleaning (zero object of cleaning), and You want/need your head seeing to (zero complement of to).
Constituents of a clause 
English is an SVO language, that is, in simple declarative sentences the order of the main components is subject–verb–object(s) (or subject–verb–complement).
A typical finite clause consists of a noun phrase functioning as the subject, a finite verb, followed by any number of dependents of the verb. In some theories of grammar the verb and its dependents are taken to be a single component called a verb phrase or the predicate of the clause; thus the clause can be said to consist of subject plus predicate.
Dependents include any number of complements (especially a noun phrase functioning as the object), and other modifiers of the verb. Noun phrase constituents which are personal pronouns or (in formal registers) the pronoun who(m) are marked for case, but otherwise it is word order alone that indicates which noun phrase is the subject and which the object.
The presence of complements depends on the pattern followed by the verb (for example, whether it is a transitive verb, i.e. one taking a direct object). A given verb may allow a number of possible patterns (for example, the verb write may be either transitive, as in He writes letters, or intransitive, as in He writes often).
Some verbs can take two objects: an indirect object and a direct object. An indirect object precedes a direct one, as in He gave the dog a bone (where the dog is the indirect object and a bone the direct object). However the indirect object may also be replaced with a prepositional phrase, usually with the preposition to or for, as in He gave a bone to the dog. (The latter method is particularly common when the direct object is a personal pronoun and the indirect object is a stronger noun phrase: He gave it to the dog would be used rather than ?He gave the dog it.)
Adverbial adjuncts are often placed after the verb and object, as in I met John yesterday. However other positions in the sentence are also possible; see English grammar: Adverbs, and for "phrasal" particles, Phrasal verb. Another adverb which is subject to special rules is the negating word not; see Negation below.
Objects normally precede other complements, as in I told him to fetch it (where him is the object, and the infinitive phrase to fetch it is a further complement). Other possible complements include prepositional phrases, such as for Jim in the clause They waited for Jim; predicative expressions, such as red in The ball is red; subordinate clauses, which may be introduced by a subordinating conjunction such as if, when, because, that, for example the that-clause in I suggest that you wait for her; and non-finite clauses, such as eating jelly in the sentence I like eating jelly.
Many English verbs are used together with a particle (such as in or away) and with preposition phrases in constructions that are commonly referred to as "phrasal verbs". These complements often modify the meaning of the verb in an unpredictable way, and a verb-particle combination such as give up can be considered a single lexical item. The position of such particles in the clause is subject to different rules from other adverbs; for details see Phrasal verb.
English is not a "pro-drop" (specifically, null-subject) language – that is, unlike some languages, English requires that the subject of a clause always be expressed explicitly, even if it can be deduced from the form of the verb and the context, and even if it has no meaningful referent, as in the sentence It is raining, where the subject it is a dummy pronoun. Imperative and non-finite clauses are exceptions, in that they usually do not have a subject expressed.
Variations on SVO pattern 
Variations on the basic SVO pattern occur in certain types of clause. The subject is absent in most imperative clauses and most non-finite clauses (see the Types of clause and Non-finite clauses sections). For cases in which the verb or a verb complement is omitted, see Elliptical clauses.
The verb and subject are inverted in most interrogative clauses. This requires that the verb be an auxiliary or copula (and do-support is used to provide an auxiliary if there is otherwise no invertible verb). The same type of inversion occurs in certain other types of clause, particularly main clauses beginning with an adjunct having negative force (Never have I witnessed such carnage), and some dependent clauses expressing a condition (Should you decide to come,...). For details see subject–auxiliary inversion and negative inversion.
A somewhat different type of inversion may involve a wider set of verbs (as in After the sun comes the rain); see subject–verb inversion.
In certain types of clause an object or other complement becomes zero or is brought to the front of the clause: see Fronting and zeroing.
Clauses with auxiliary verbs 
In many English clauses, the finite verb is an auxiliary verb, whose complement is some type of non-finite clause. For example, in the clause he is eating his dinner, the finite verb is the auxiliary is, whose complement is the participial clause eating his dinner. In some cases the non-finite clause itself has an auxiliary as its main verb, with another embedded non-finite clause as complement. For example:
- He has (been (eating his dinner)).
Here eating his dinner is the complement of been, and been eating his dinner is the complement of has.
The form of each lexical or auxiliary verb (apart from the first) is determined by the auxiliary preceding it. The first auxiliary is conjugated as a finite verb in present or past tense: the modals are invariant, but the other auxiliaries may take the forms have, has, had, am, is, are, be (subjunctive), was, were, do, does, did. (If the clause being considered is a non-finite clause, then the initial auxiliary form may be having, (to) have, being, or (to) be.)
The principal auxiliaries and the verb forms they govern are:
- Modal verbs (will, can, could, etc.). They govern a bare infinitive (or to-infinitive in the case of ought and used).
- The verb have (and its inflected forms) to express perfect aspect. These govern a past participle (with an active meaning).
- The verb be (and inflected forms) to express progressive aspect. These govern a present participle.
- The verb be (and inflected forms) to express passive voice. These govern a past participle (used passively, i.e. with a zero object or preposition complement).
- The verb do (and inflected forms) to supply an auxiliary in functions where one is required, or to provide emphasis. This is described in more detail in the article on do-support.
A modal verb, if present, comes first. Any other auxiliaries come in the order listed above, namely perfect have followed by progressive be followed by passive be. The auxiliary do is not used in combination with any other auxiliary. Otherwise, the above auxiliaries can be used in any combination (but with no more than one instance from each group).
A clause containing the maximum number of auxiliaries might therefore be I will have been being operated on for six hours. Here the modal will is the finite verb; perfect have is in bare infinitive form (since it follows a modal), progressive be is in the past participle form been (following perfect have), passive be is in the present participle form being (following progressive be), and the lexical verb is in the past participle form operated (following passive be; here it is the dependent preposition on that has zero complement).
Constructions of this type serve a variety of functions, including the expression of aspect, voice and modality. The meaning of combinations of these auxiliary verbs are presented in more detail later in this article.
Some of these constructions are described, particularly in teaching contexts, as tenses – for example, is eating is represented as the "present progressive tense" of eat. (This terminology is rejected by many theoretical grammarians, since the construction does not serve purely to indicate present time, but also encodes aspectual information.) The series of auxiliaries and non-finite verb form is treated as a unit. Thus in the examples above, the strings is eating and has been eating may be presented as forms of the verb eat, with his dinner serving as their object. (From a theoretical perspective, these verb series are examples of catenae.)
Non-finite constructions exist for combinations of auxiliary verbs other than the modals verbs or do:
- infinitive: (to) take, (to) be taken, (to) be taking, (to) have been taking, etc.
- present participial (or gerund): taking, being taken, having taken, etc. (but not normally in the progressive cases)
The verbs ought and used differ from other modals in that they require the to-infinitive rather than the bare infinitive: He ought to go; We used to go (for this reason they are not always classified as modals). There are certain other auxiliary-like expressions that are variously classified:
- (be) going to
- have to
- am to, was to, etc.
- (be) able to
- (be) about to
Fronting and zeroing 
In interrogative and relative clauses, wh-fronting occurs; that is, the interrogative word or relative pronoun (or in some cases a phrase containing it) is brought to the front of the clause: What did you see? (the interrogative word what comes first even though it is the object); The man to whom you gave the book... (the phrase to whom, containing the relative pronoun, comes to the front of the relative clause; for more detail on relative clauses see English relative clauses).
Fronting of various elements can also occur for reasons of focus; occasionally even an object or other verbal complement can be fronted rather than appear in its usual position after the verb, as in I met Tom yesterday, but Jane I haven't seen for ages. (For cases in which fronting is accompanied by inversion of subject and verb, see negative inversion and subject–verb inversion.)
In certain types of non-finite clause ("passive" types; see Non-finite clauses above), and in some relative clauses, an object or a preposition complement is absent (becomes zero). For example, in I like the cake you made, the words you made form a reduced relative clause in which the verb made has zero object. This can produce preposition stranding (as can wh-fronting): I like the song you were listening to; Which chair did you sit on?
A clause is negated by the inclusion of the word not:
- In a finite indicative clause in which the finite verb is an auxiliary or copula, the word not comes after that verb, often forming a contraction in n't: He will not (won't) win.
- In a finite indicative clause in which there is otherwise no auxiliary or copula, do-support is used to provide one: He does not (doesn't) want to win.
- In the above clause types, if there is inversion (for example, because the sentence is interrogative), the subject may come after the verb and before not, or after the contraction in n't: Do you not (Don't you) want to win? (In the case of inversion expressing a condition, the contracted form is not possible: Should you not (not: *Shouldn't you) wish to attend...
- Negative imperatives are formed with do-support, even in the case of the copula: Don't be silly!
- The negative of the present subjunctive is made by placing not before the verb: ...that you not meet us; ...that he not be punished. The past subjunctive were is negated like the indicative (were not, weren't).
- A non-finite clause is negated by placing not before the verb form: not to be outdone (sometimes not is placed after to in such clauses), not knowing what to do.
Elliptical clauses 
Certain clauses display ellipsis, where some component is omitted, usually by way of avoidance of repetition. Examples include:
- omitted verb between subject and complement, as in You love me, and I you (where the same verb love is understood between I' and you).
- tag questions, as in He can't speak French, can he? (where the infinitive clause speak French is understood to be the dependent of can).
- similar short sentences or clauses such as I can, there is, we will, etc., where the omitted non-finite clause or other complement is understood from what has gone before (for examples involving inversion, such as so/neither do I, see subject–auxiliary inversion).
For more analysis and further examples, see Verb phrase ellipsis.
Meanings of clauses using auxiliary verbs 
The various constructions with auxiliary verbs (see Clauses with auxiliary verbs above) can be used to express aspect (with perfective have and progressive be), voice (with passive be) and modality (with the modal verbs).
English clauses can be described as having progressive aspect, perfect aspect, neither ("simple aspect"), or both ("perfect progressive aspect"). They can also be described as having active voice or passive voice. The following table shows these combinations:
|Perfect progressive, active||has||been||taking|
|Perfect progressive, passive||has||been||being||taken|
The constructions given above are third-person singular present indicative. However, by changing the form of the finite (i.e. first) verb in each case, equivalent forms can be constructed for other persons and numbers, for past tense, and for imperative and subjunctive mood (although the imperative is not normally used with perfect aspect, and only rarely with progressive).
The meanings of the aspects are as follows:
- The simple constructions can be used to express habitual action. In many contexts they can also be used to express single completed actions.
- Progressive constructions denote ongoing activity at a specific point of time or continuous activity over an extent of time.
- Perfect constructions are used to express actions or events that happened before a point in time, with an emphasis on the continuing effects of these at this point of time. (See also Relative and absolute tense.)
- Perfect progressive constructions are used to express ongoing activity that extends to a certain point in time.
(The meaning of the passive voice can also be expressed with get in some cases, particularly when adverse consequences are implied, as in She got injured. However get is not a grammatical auxiliary; for example, it requires do-support for negation and questions.)
Modal verbs can also be used, such as "will" used as above in future constructions and "would" in conditional constructions. These serve as uninflected auxiliary verbs, even in the third person singular. Most of these have multiple modal uses, depending on context. With the exception of ought, all are followed by the short form of the main verb's infinitive (that is, without the particle to). Dare and need, are infrequently used as modals and are much more frequently used instead as main verbs that are inflected with -s in the present tense third person singular; when they are used as main verbs, the infinitive following them includes the particle to.
This is illustrated in the table below with the modal might.
The modals are invariant, so in this case it is not possible to inflect for tense or mood (except insofar as certain modals express these categories; for example, could may serve as a past tense of can). There are no imperative or non-finite forms (periphrasis may be used in some cases; for example, infinitive clauses can be made with to be able to... or to be going to...).
The modal will, in some of its uses, expresses future time. Hence constructions using will as the modal in the above schema are often referred to as being instances of a future tense. Thus forms like will take can be called the simple future, will have taken the future perfect, and so on. Analogous terminology is used for the forms with would (sometimes should); these are referred to as conditional (or "future-in-the-past") forms. Sometimes shall and should are also used in this way: see shall and will.
Simple constructions 
The simple constructions can be used to express habitual action. In many contexts they can also be used to express single completed actions.
|Present||He writes||He does not write||Does he write?||Does he not write? / Doesn't he write?|
|Past||He wrote||He did not write||Did he write?||Did he not write? / Didn't he write?|
|Future (will)||He will write||He will not write||Will he write?||Will he not write? / Won't he write?|
|Conditional (would)||He would write||He would not write||Would he write?||Would he not write? / Wouldn't he write?|
The passive voice is formed using the appropriate form of the verb be followed by the past participle (more accurately called the passive participle in this context) of the main verb, e.g. "He is written."
The simple present has three main uses in English: First, it often identifies habitual or customary action referring to no specific time frame:
- He writes about beavers (in the past, present, and future)
Second, it is used with stative verbs to refer to a present situation:
- She knows a lot about beavers
Third, it can have a future meaning in two contexts (though its use as an indicator of futurity is much less common than in many other languages):
- Scheduled future: She goes to Milwaukee on Tuesday, I arrive tomorrow at 5:00.
- Future in a dependent clause: I will see you when I get there, I will go tomorrow if I feel like it, It will be Tuesday when I see you.
The simple present has an intensive or emphatic construction with "do": He does write. In the negative and interrogative constructions, of course, this is identical to the non-emphatic constructions. It is typically used as a response to the question Does he write, whether that question is expressed or implied, and says that indeed, he does write.
The different syntactic behavior of the negative particle not and the negative inflectional suffix -n't in the interrogative constructions is also worth noting. In formal literary English of the sort in which contractions are avoided, not attaches itself to the main verb: Does he not write? When the colloquial contraction -n't is used, this attaches itself to the auxiliary do: Doesn't he write? This in fact is a contraction of a more archaic word order, still occasionally found in poetry: *Does not he write?
The simple past is also called the preterite.
The preterite is used for the English simple (non-iterative or iterative, but not progressive) past tense. He wrote two more chapters about the dam at Kashagawigamog Lake.
This tense is used for a single event in the past (I went there yesterday), for past habitual action (I went there every day for a year), and in chronological narration. Like the present simple, it has an emphatic variant with "do": he did write.
The simple past is distinct from the present perfect:
- I ate fish (Simple statement of event[s] occurring in the past, with no reference to the present state.)
- I have eaten fish (My present state is that eating fish is in my past.)
The preterite, when used to indicate habitual aspect, can often be replaced by a compound construction:
- When I was young, I played football or When I was young, I played football every Saturday. (past tense unmarked for aspect, but by lexical context implying habituality, with either a specific or a non-specific time frame)
- When I was young, I used to play football. (periphrastic construction explicitly indicating habituality, with a relatively non-specific time frame in the past)
- When I was young, I would play football every Saturday. (periphrastic construction explicitly indicating habituality, with a specific time frame in the past)
English does not have a dedicated future tense in the sense of a morphological form that always indicates what the speaker views as facts about the future.
Shall can be used in place of will: see the article Shall and Will for a discussion of the two auxiliary verbs used to form the simple future in English.
Will and would can be used with a different meaning to futurity or conditionality:
- You will obey me! (insistence)
- I will not do it! (refusal, i.e. negative insistence)
- He will probably be home now. (probability)
- Usually, whenever I get home, I will drink a cup of tea. (present habitual action)
- At that time, I would always drink tea in the morning. (past habitual action, similar to "used to")
- I would not do that (if I were you). (suggestion, or implied conditional action)
The will construction can be used to indicate what the speaker views as facts about the future:
- The sun will rise tomorrow at 6:14 AM.
It can also indicate a combination of futurity and intentional or volitional modality:
- He will go there if he can.
- I will pass this exam.
It can also indicate predictive modality — what the speaker intends as predictions about the future:
- It will rain later this week.
The will construction is occasionally used for statements about the present to indicate that they are speculative:
- Jack: "I have not eaten a thing all day."
- Jill: "Well, I suppose you will be hungry now."
- Jack: "There is a woman coming up the drive."
- Jill: "That will be my mother."
The will construction can be used to indicate strong volition in the present in the first person:
- At this moment I will tolerate no dissent.
It can also be used to indicate habituality in the past, present and future:
- He will make trouble, won't he?
There is also a future with "go" which is used with the infinitive of the action verb especially for intended actions and for the weather, and which is generally more common in colloquial speech:
- I am going to write a book some day.
- I think that it is going to rain.
The will/shall construction can be used for spontaneous decisions:
- Jack: "I think that we should have a barbecue!"
- Jill: "Good idea! I shall go get the coal."
Present subjunctive 
This form is always identical to the infinitive. This means that apart from the verb to be, it is distinct from the indicative present only in the third person singular and the obsolete second person singular.
It is used to express wishes about the present or future:
- God save our queen. (Not: God saves our queen, which means that it actually happens)
It can be used (in formal writing) to express present doubt, especially after if, whether, and lest and in set phrases:
- If that have any validity....
- If that be true,....
- If he need go,....
- If music be the food of love,....
- Whether that be true or not,....
- Lest he arrive too soon,....
- Be that as it may,....
The subordinate conjunction whether can be replaced by inversion of be and the subject:
- Be that true or not,....
It is also used in a mandative sense:
- He insists that his son have a more conventional celebration. (He strongly wants that to be true in the future; contrast with the indicative usage He insists that his son has a more conventional celebration, in which he asserts that it is a fact.)
- It is important that the process be carried out accurately.
- I shall work for him on condition that he pay me weekly.
The present subjunctive can be written in the passive voice as in
- If it be written,....
The conditional present is formed by combining the modal auxiliary would (never *woulds, not even in the third person singular) with the infinitive (without to) of the main verb:
The conditional present is used principally in a main clause accompanied by an implicit or explicit doubt or "if-clause"; it may refer to conditional statements in present or future time:
- I would like to pay now if it is not too much trouble. (in present time; doubt of possibility is explicit)
- I would like to pay now. (in present time; doubt is implicit)
- I would go tomorrow if she asked me. (in future time; doubt is explicit)
- I would go tomorrow. (in future time; doubt is implicit)
Some varieties of English regularly use would (often shortened to (I)'d) in if clauses, but this is often considered non-standard: If you'd leave now, you'd be on time. Such use of would is widespread especially in spoken US English in all sectors of society, but these forms are not usually used in writing that is more formal. Nevertheless, some reliable sources simply label this usage as acceptable US English and no longer label it as colloquial.
There are exceptions, however, where would is used in British English too in seemingly counterfactual conditions, but these can usually be interpreted as a modal use of would: If you would listen to me once in a while, you might learn something. In cases in which the action in the if clause takes place after that in the main clause, use of would in counterfactual conditions is however considered standard and correct usage in even formal UK and US usage: If it would make Bill happy, I'd [I would] give him the money.
The auxiliary verbs could and might can also be used to indicate the conditional mood, as in the following:
- If the opportunity were here, I could do the job (= "If the opportunity were here, I would be able to do the job")
- If the opportunity were here, I might do the job (= "If the opportunity were here, maybe I would do the job")
Progressive constructions 
Progressive constructions denote ongoing activity at a specific point of time or continuous activity over an extent of time. All verbal constructions can be made progressive (e.g. "I have written" → "I have been writing"), and these constructions are very common. Progressive constructions are also known as "continuous".
|Present||He is writing||He is not writing||Is he writing?||Is he not writing? / Isn't he writing?|
|Past||He was writing||He was not writing||Was he writing?||Was he not writing? / Wasn't he writing?|
|Future (will)||He will be writing||He will not be writing||Will he be writing?||Will he not be writing? / Won't he be writing?|
|Conditional (would)||He would be writing||He would not be writing||Would he be writing?||Would he not be writing? / Wouldn't he be writing?|
The passive voice of the progressive is formed by the present progressive of to be ("been") followed by the past participle of the main verb ("written"), e.g. "He is being written."
An important difference between the present progressive tense in English and many other languages with similar tenses (e.g. Spanish) is that the English present progressive must be used in many circumstances. In particular, a statement about an ongoing action at the present time normally must use the progressive ("I am writing a letter now" but not "*I write a letter now"). The simple present is used in the following circumstances:
- A habitual statement: "I write letters every day."
- A general statement: "People write letters when they cannot telephone."
- A narrative action told in the present tense: "I get home, then I write a letter, then I eat dinner, then the phone rings and it's my girlfriend."
- With verbs that refer to states rather than actions: "I feel lonely", "I see a bear", "I have a large car", "I am a doctor".
In the latter cases, the progressive is often possible, sometimes with different implications. Generally, it implies an action rather than a state, and an ongoing, often temporary situation. For example, "I am feeling lonely" and "I am seeing a bear" specifically emphasize the perception of the feeling at the current time, which is implied to be temporary.
With "have" and "be" the present progressive is even clearer in imparting a meaning of "currently ongoing action". Hence "??I am having a large car" would sound quite strange, and be almost uninterpretable, while "?I am being a doctor" still sounds strange but potentially might mean "I'm not a doctor but I'm temporarily trying to act like one". But there are a number of quite acceptable usages of progressive "have" and "be":
- "I have a baby" (a small child currently exists in the world and I am its parent) vs. "I am having a baby" (I am giving birth right now to a child)
- "John is a pest" (John generally acts in an annoying way) vs. "John is being a pest" (right now, John is acting in a way that is annoying)
- "I have a problem" (something in my world is wrong) vs. "I am having a problem" (right now, something in my world is going wrong); e.g. "I am having a problem finding my glasses" (right now, I'm looking for my glasses but I can't find them) vs. "I have a problem finding my glasses" (I often lose my glasses and can't find them).
This construction describes the simple engagement in a present activity, with the focus on action in progress "at this very moment". It too can indicate a future, particularly when discussing plans already in place: I am flying to Paris tomorrow. Used with "always" it suggests irritation; compare He always does that (neutral) with He is always doing that (and it annoys me). Word order differs here in the negative interrogative between the more formal is he not writing and the colloquial contraction isn't he writing?
The past progressive construction indicates ongoing action in the past
This construction is typically used for two events in parallel:
- While I was washing the dishes, my wife was walking the dog.
It can also be used for an interrupted action (the past simple being used for the interruption):
- While I was washing the dishes, I heard a loud noise.
Further, it can be used to indicate continuing action at a specific time in the past:
- At three o'clock yesterday, I was working in the garden.
It can also be used to refer to past action that occurred over a range of time and is viewed as an ongoing situation:
- I was working in the garden all day yesterday (it was an ongoing process), as opposed to I worked in the garden all day yesterday (and I am viewing all of that action as a unitary event)
This construction is used especially to indicate that an event will be in progress at a particular point in the future: This time tomorrow I will / shall be taking my driving test.
The passive construction It will be being written is rarely used. If it is desired to express future progressivity in the passive voice, the construction It will be in the process of being written can be used.
The conditional present progressive is used for the continuous aspect of the conditional construction; it describes a situation that would now be prevailing had it not been for some intervening event:
- Today she would be exercising if it were not for her injury.
- He would be working today had he not been allowed time off.
(For the use of would in both clauses, see note and sources at end of section on conditional above.)
The passive voice of the conditional progressive progressive can be formed as It would be being written, but since this construction is awkward the form It would be in the process of being written would be more common.
Perfect constructions 
Perfect constructions are used to express actions or events that happened before a point in time, with an emphasis on the continuing effects of these at this point of time.
The following table shows examples of perfect constructions being used with the pronoun "he":
|Present||He has written||He has not written||Has he written?||Has he not written? / Hasn't he written?|
|Past||He had written||He had not written||Had he written?||Had he not written? / Hadn't he written?|
|Future (will)||He will have written||He will not have written||Will he have written?||Will he not have written? / Won't he have written?|
|Conditional (would)||He would have written||He would not have written||Would he have written?||Would he not have written? / Wouldn't he have written?|
The passive voice is formed with by the present perfect of to be ("been") followed by the past participle of the main verb, e.g. "He has been written."
The present perfect was traditionally just called the perfect.
The distinction between the past (I did) and the present perfect (I have done) can be subtle. In general, the present perfect occurs in cases where there is an explicitly or implicitly established present frame of reference. When the frame of reference is explicit, such as in the sentence "Whenever I get home, usually John has already arrived", the usage of the present perfect is clear, but in other cases it is less obvious.
- When an action indicates a change of state, the present perfect indicates that the resulting state still applies. "I have eaten" means "... and I'm no longer hungry", whereas "I ate" has no such implication. "The sign has changed" means "... and it is now different, so pay attention", whereas "The sign changed" does not specifically have that meaning; e.g. perhaps the sign changed back again.
- When a repeated or prolonged action is specified, the present perfect indicates that the time period in question goes up to the present. "I have visited Paris three times" specifically means "... in my life, up to the present time" while "I visited Paris three times" would normally only be used when a smaller time period is specifically indicated. "I have lived in Paris for five years" specifically means "I lived in Paris for five years some uncertain time ago and I don't live there now. I have an experience of Paris" (it is, however, relevant to a current conversation; the importance is that of an experience rather than of the specific time of getting that experience) while "I lived in Paris for five years" implies "You (the listener) know what specific time I am talking about and the time when I lived in Paris is as important as the fact that I lived there." If one wants to imply that he/she still lives in Paris, he/she should ideally say: "I have been living in Paris for 5 years". This would imply an ongoing process of still living in Paris. However, people might use Present Perfect for an ongoing process, too and that is why you might hear a lot of follow up questions in conversations.
- When an explicitly past frame of reference is established by mentioning a particular time in the past, the present perfect cannot normally be used. That is, "I ate two minutes ago" not "*I have eaten two minutes ago" regardless of whether I'm hungry or not currently.
- With "already" or "yet", traditional usage calls for the present perfect: "Have you eaten yet? Yes, I've already eaten." However, current informal American speech tends to use the simple past: "Did you eat yet? Yes, I ate already."
This construction indicates that a past event has one of a range of possible relationships to the present. This relationship may involve a focus on present result: He has written a very fine book (and look, here it is, we have it now). Alternatively, it may indicate a period which includes the present: I have lived here since my youth (and I still do). Compare: Have you written a letter this morning? (it is still morning) with Did you write a letter this morning? (it is now afternoon). The perfect construction is frequently used with the adverbs already or recently or with since clauses. The present perfect can identify habitual and continuing actions (I have written letters since I was ten years old.), continuous and ongoing actions (I have lived here for fifteen years.), or completed actions that still affect the present situation (I have visited Paris twice (and the memory of the experience is still with me)).
In addition to these normal uses where the event is viewed from the present, the “have done” construct is used with a future perspective in temporal clauses where other languages would use the future perfect: When you have written it, show it to me.
The term "perfect" was first applied in discussions of Latin grammar, to refer to a tense which expresses a completed action ("perfect" in the sense of "finished"). It was then applied to a French tense which has a similar use to the Latin perfect, and then was transferred to the English tense which looks morphologically something like the French perfect. In fact, the English perfect is often used precisely in situations where Latin would use the imperfect — for past actions which are not finished but continue into the present.
Have got 
In colloquial English, particularly British English, the present perfect of the verb get, namely have got or has got, is frequently used in place of the simple present indicative of have (i.e. have or has) when denoting possession, broadly defined. For example:
- Formal: I have three brothers; Does he have a car?
- Informal: I've got three brothers; Has he got a car?
Note that in American English, the form got is used in this idiom, even though the standard past participle of get is gotten.
The same applies in the expression of present obligation: I've got to go now may be used in place of I have to (must) go now.
In very informal registers, the contracted form of have or has may be omitted altogether: I got three brothers.
The past perfect is also known as the pluperfect; it is formed by combining the preterite of to have with the past participle of the main verb:
The past perfect is used when the action occurred in the past before another action in the past. It is used when speaking of the past to indicate the relative time of two past actions, one occurring before the other; i.e. a "past before the past".
The past time of perspective could be stated explicitly:
- He had already left when we arrived.
or it can be understood from previous information:
- I was eating....I had invited Jim to the meal but he was unable to attend. (i.e., I invited him before I started eating)
The past time of perspective can simply be implied by the context:
- I had lost my way. (understood as prior to a later but still past event I am now describing, for example, "when I met the bear".)
It is sometimes possible to use the simple past instead of the past perfect, but only where there is no ambiguity in the meaning. For instance, the second example above could be written:
- I was eating....I invited Jim to the meal but he was unable to attend
Understood within the above context, this still means that I first invited Jim then later ate the meal (without him).
However, concurrent past events are also possible, indicated by dual simple past tenses in both verbs. Consider the following:
- He left when we arrived.
This means both past events happened at the same time: he left at the same time as we arrived.
The past perfect can also be used to express a counterfactual statement about the past:
- If you had done the cleaning by now, you would not need to do it now
Here, the first clause refers to an unreal state in the past (without any comparison of the timing of multiple past events), and the entire construction is a conditional sentence.
The future perfect is formed by combining, in this order, will or shall, the auxiliary verb have, and the past participle of the main verb. It indicates an action that either is completed sometime prior to a future time of perspective or an ongoing action that continues to a future time of perspective:
- I shall have finished my essay by Thursday.
- By then she will have been there for three weeks.
The conditional perfect construction is used for conditional situations occurring in the past; it expresses thoughts which are or may be contrary to present fact:
- I would have set an extra place if I had known you were coming. (The fact that an extra place was not set is implicit; the conditioning event (I had known) is explicit)
- I would have set an extra place, but I did not because Mother said you were not coming. (The fact that a place was not set is explicit; the conditioning event is implicit)
- I would have set an extra place. (The fact that a place was not set is implicit, and the conditioning event is implicit)
Some varieties of English regularly use would have (often shortened to (I)'d have) in if clauses, but this is often non-standard: If you (would)'ve told me, we could've done something about it. Such use of would is widespread especially in spoken US English in all sectors of society, but is incorrect and is not usually used in more formal writing. (See note and sources at end of section on conditional above.)
There are exceptions, however, where would is used in British English too in seemingly counterfactual conditions, but these can usually be interpreted as a modal use of would: If you would have listened to me once in a while, you might have learned something. In cases in which the action in the if clause takes place after that in the main clause, use of would in if clauses is however considered standard and correct usage in even formal UK and US usage: If it would have made Bill happy, I'd [I would] have given him the money. (See note and sources at end of section on conditional above.)
Perfect progressive constructions 
Perfect progressive constructions (or perfect continuous constructions) are used to express ongoing activity that extends to a certain point in time.
|Present||He has been writing||He has not been writing||Has he been writing?||Has he not been writing? / Hasn't he been writing?|
|Past||He had been writing||He had not been writing||Had he been writing?||Had he not been writing? / Hadn't he been writing?|
|Future (will)||He will have been writing||He will not have been writing||Will he have been writing?||Will he not have been writing? / Won't he have been writing?|
|Conditional (would)||He would have been writing||He would not have been writing||Would he have been writing?||Would he not have been writing? / Wouldn't he have been writing?|
For passive voice clauses, the present participle ("writing") is replaced with "being" followed by the past participle ("being written").
It is used for unbroken action in the past which continues right up to the present. I have been writing this paper all morning (and still am).
The present perfect progressive is used for denoting the action which was in progress and has just finished or is still going on. For example,
- Why are your eyes red? – I have been crying since morning. (The action has already finished but was in progress for some time)
- She has been working here for two years already and she is happy. (The action is still in progress).
Sentences referring to an expanse of time use the present perfect continuous if ongoing action (not a static situation) is referred to. For example,
- How long have you been working here? — I have been working here for three years
However, with stative verbs (such as see, want, like, etc.), or if the situation is considered permanent, the present perfect non-progressive construction is used. For example,
- How long have you known her? — I have known her since childhood
Thus, if the whole period is referred to, for is used, but when the reference is to the starting point of the action, since is used.
The construction It has been being written, while following the usual pattern for the formation of the passive voice, is very rarely used. Occasionally, when it is desired to express the receiving of an action in the past and continuing to the present, the phrasal construction It has been in the process of being written is used. Here the present perfect construction is applied to to be, and the continuity and the passive voice are applied to the main verb in non-finite form in a noun phrase.
The past perfect progressive is also known as the pluperfect progressive , the past perfect continuous, and the pluperfect continuous. It is formed by combining, in this order, the preterite of to have, the past participle of to be, and the present participle of the main verb.
The past perfect progressive relates to the past perfect as the present perfect progressive relates to the present perfect.
The construction It had been being written is very rarely used. To convey the past perfect progressive in the passive voice, the construction It had been in the process of being written can be used.
The future perfect progressive, also called the future perfect continuous, is formed by combining, in this order, will or shall, the auxiliary have, the past participle been, and the present participle of the main verb.
This construction is used for an event that will still be in progress at a certain point in the future: By 8:00 he will have been writing for five hours (and will still be doing so).
The construction It will have been being written is never used. The construction It will have been in the process of being written can be used to indicate the continuous receiving of an action prior to some time in the future.
Rather than the very rarely used awkward construction It would have been being written, the conditional perfect progressive can be expressed in the passive voice as in It would have been in the process of being written.
Subjunctive constructions 
Past subjunctive 
The past subjunctive is used to express hypotheses about the present or future: it is used to describe unreal or hypothetical conditions. It consists of the verb were in all persons and numbers (including the first and third persons singular), either as the main verb or as a helping verb combined with the infinitive of the main verb.
It usually appears in "if clauses" of conditional sentences. Examples include:
- If I were rich, I would retire to the South of France.
- If I were a boy,....
Especially in formal usage, if may be omitted and the order of the subject and were inverted:
- Were I to speak, I would do so softly. (This is identical in meaning to If I were to speak,....)
When if means when (a fact) then the indicative is used. Compare
- If I were walking down the road, I would greet him. (The subjunctive is used for a hypothetical present situation; the main clause is in the conditional.)
- If I was walking down the road, I would greet him. (The indicative is used for a fact about habitual actions in the past; the main clause is in the past time and habitual aspect.)
The imperfect subjunctive is also used in "that clauses" after a wish:
- I'd rather that it were more substantial.
- I wish she were here.
This last example can be contrasted with I want her to be here, in which the indicative rather than the subjunctive is used because there is a substantial possibility that the hypothesis is (or will be) true.
The imperfect subjunctive can be written in the passive voice as in
- If it were written....
- Were it written....
Future subjunctive 
A future subjunctive for use in "if clauses" can be constructed using the conjugated form of the verb "to be" plus the infinitive (including the particle to) or by using the modal auxiliary verb "should" (though the should form is very unusual in American English):
- If I were to die tomorrow, then you would inherit everything.
- If I should go, then will / would you feed the hens?
These constructions can alternatively be expressed with inversion of the order of were or should and the subject, with if omitted:
- Were I to die tomorrow, then you would inherit everything.
- Should I go, then will / would you feed the hens?
If the were to constructions is used in the "if clause", the word would is used in the main clause; if the should form is used in the "if clause", either will or would can be used in the main clause, depending on whether the event is very hypothetical (leading to the use of would) or is quite possible (permitting the use of will).
The passive voice can be applied to the future subjunctive as in any of the following:
- If it were to be written tomorrow,....
- Were it to be written tomorrow,....
- If it should be written tomorrow,....
- Should it be written tomorrow,....
Uses of non-finite constructions 
The various types of non-finite clauses described above have a number of uses besides the constructions with auxiliaries already described.
An infinitive phrase begins with the base form of the verb. Infinitive phrases can be viewed as part of finite clauses where they are introduced in verb catenae by an auxiliary verb or by a certain limited class of main verbs. They are also often frequently introduced by a main verb followed by the particle to. Further, infinitives introduced by to can function as noun phrases, or even as modfifiers of nouns. The following table illustrates these environments:
Infinitive Introduced by a (modal) auxiliary verb Introduced by a main verb Introduced by a main verb plus to Functioning as noun phrase Functioning as the modifier of a noun laugh Do not laugh! That made me laugh. I tried not to laugh. To laugh would have been unwise. the reason to laugh leave They may leave. We let them leave. They refused to leave. To leave was not an option. the thing to leave behind expand You should expand the explanation. We had them expand the explanation. We hope to expand the explanation. To expand the explanation would have been folly. the effort to expand
An infinitive phrase begins with the bare form of the first verb, and is usually co-ordinated by the word "to":
- I need to get my work done
- For them to be with us in this time of crisis is evidence of their friendship.
When the semantic agent of the verb phrase occurs as the object in the co-ordinating clause, "to" does not occur:
- I heard them shout.
Infinitive phrases are used after particular verbs such as "want" or "need".
The placement of an adverbial modifier directly after the to of an infinitive phrase (to slowly drift away) is called a split infinitive, and is sometimes regarded as a grammatical or stylistic error.
Present participle and gerund 
A present participle phrase uses the present participle form of the verb, ending in "-ing".
It may be used in progressive constructions:
Infinitive Progressive active participle fix The guy is fixing my bike. open the flower opening up support the news supporting the point drive She is driving our car.
The present participle may be used in non-finite constructions such as the following:
- Having spoken, he turned and left.
- Looking out the window, he saw a car go by.
- Having been beaten at poker, he had little money left.
- I saw them digging a hole.
The present participle form of a verb may function as a noun, in which case it is referred to as a gerund. Gerunds typically appear as subject or object noun phrases, or even as the object off a preposition:
Infinitive Gerund as subject Gerund as object Gerund as object of a preposition solve Solving problems is satisfying. I like solving problems. No one is better at solving problems. jog Jogging is boring. He has started jogging. Before jogging, she stretches. eat Eating too much made me sick. She avoids eating too much. That prevents you from eating too much. investigate Investigating the facts won't hurt. We tried investigating the facts. After investigating the facts, we made a decision.
Often distinguishing between a gerund and a progressive active participle is not easy; the line between the two non-finite verb forms is not clear.
A present participle may function as an adjective modifying a noun: "The dancing girls".
Past participle 
The past participles of strong verbs in Germanic languages are irregular (e.g. driven); their form is idiosyncratic. The past participles of weak verbs, in contrast, are regular; their form is formed with the suffix -ed (e.g. fixed, supported, opened).
Past participles are used in perfect and passive constructions:
Infinitive Perfect active participle Passive participle fix He has fixed my bike My bike was fixed. open The flower has opened up. The flower has been opened up. support The news has supported the point. the point supported by the news drive She has driven our car. Our car should be driven often.
- With these words spoken, he turned and left.
As with present participles, past participles may function as adjectives: "the burnt logs".
- Carter & McCarthy 2006, p. 304
- Language Log, "What's will?" (December 10, 2008)
- Carter & McCarthy 2006, p. 306
- "Conditional would is sometimes used in both clauses of an if-sentence. This is common in spoken American English."
- Pearson Longman, Longman Exams Dictionary, grammar guide: It is possible to use would in both clauses in US English but not in British English: US: The blockades wouldn't happen if the police would be firmer with the strikers. Br: The blockades wouldn't happen if the police were firmer with the strikers.
- To stress willingness of wish, you can use would or will in both clauses of the same sentence: If the band would rehearse more, they would play better. If the band will rehearse more, they will play better. Both mean the same. (based on the examples and explanations from Practical English Usage, Michael Swan, Oxford)
- Have got, Peter Viney, wordpress.com