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In linguistics, a dependent clause (or a subordinate clause) is a clause that augments an independent clause with additional information, but which cannot stand alone as a sentence. Dependent clauses either modify the independent clause of a sentence or serve as a component of it. Some grammarians use the term subordinate clause as a synonym for dependent clause. Other grammars use subordinate clause to refer only to adverbial dependent clauses. There are also different types of dependent clauses, including noun clauses, relative (adjectival) clauses, and adverbial clauses.
Dependent words 
In Indo-European languages, a dependent clause usually begins with a dependent word. One kind of dependent word is a subordinating conjunction. Subordinating conjunctions are used to begin dependent clauses known as adverbial clauses, which act like adverbs. In the following examples, the adverbial clauses are bold and the subordinating conjunctions are italicized:
- Wherever she goes, she leaves an item of luggage behind.
- (The adverbial clause wherever she goes modifies the verb leaves.)
- Bob enjoyed the movie more than I did.
- (The adverbial clause than I did modifies the adverb more.)
A subordinating conjunction can also introduce a noun clause:
- I know that he likes me.
- (The noun clause that he likes me serves as the object of the main-clause verb know.)
Another type of dependent word is the relative pronoun. Relative pronouns begin dependent clauses known as relative clauses; these are adjective clauses, because they modify nouns. In the following example, the relative clause is bold and the relative pronoun is italicized:
- The only one of the seven dwarfs who does not have a beard is Dopey.
- (The adjective clause who does not have a beard describes the pronoun one.)
A relative adverb plays the role of an adverb in a relative clause, as in
- That is the reason why I came.
- (The relative clause why I came describes the noun reason, and within the relative clause the adverb why modifies the verb came.)
- That is the place where he lives.
- (The relative clause where he lives describes the noun place, and within the relative clause the adverb where modifies the verb lives.)
An interrogative word can serve as an adverb in a noun clause, as in
- No one understands why you need experience.
- (The noun clause why you need experience functions as the direct object of the main-clause verb "understands", and within the noun clause why serves as an adverb modifying need.)
Noun clause 
A noun clause can be used like a noun. It can be a subject, predicate nominative, direct object, appositive, indirect object, or object of the preposition. Some of the English words that introduce noun clauses are that, whether, who, why, whom, what, how, when, whoever, where, and whomever. Notice that some of these words also introduce adjective and adverbial clauses. A clause is a noun clause if a pronoun (he, she, it, or they) could be substituted for it.
- I know who said that. (I know it.) (The dependent clause serves as the object of the main-clause verb "know".)
- Whoever made that assertion is wrong. (He/she is wrong.) (The dependent clause serves as the subject of the main clause.)
Sometimes in English a noun clause is used without the introductory word.
- I know that he is here.
- I know he is here. (without "that")
In some cases, use of the introductory word, though grammatically correct, may sound cumbersome in English, and the introductory word may be omitted.
- I think that it is pretty. (less common)
- I think it is pretty. (more common)
Relative (adjectival) clause 
In Indo-European languages, a relative clause, also called an adjective clause or an adjectival clause, will meet three requirements:
- Like all dependent clauses, it will contain a verb (and it will also contain a subject unless it is a non-finite dependent clause). However, in a pro-drop language the subject may be a zero pronoun—that is, the pronoun may not be explicitly included because its identity is conveyed by a verbal inflection.
- It will begin with a relative adverb [when, where, or why in English] or a relative pronoun [who, whom, whose, that, or which in English]. However, the English relative pronoun may be omitted and only implied if it plays the role of the object of the verb or object of a preposition in a restrictive clause; for example, He is the boy I saw is equivalent to He is the boy whom I saw, and I saw the boy you are talking about is equivalent to the more formal I saw the boy about whom you are talking.
- The relative clause will function as an adjective, answering questions such as "what kind?", "how many?" or "which one?".
The adjective clause in English will follow one of these patterns:
- Relative Pronoun [Functioning as Object of Verb] + Subject + Verb
- This is the ball that I was bouncing.
- Relative Adverb + Subject + Verb (possibly + Object of Verb)
- That is the house where I grew up.
- That is the house where I met her.
- Relative Pronoun [Functioning as Subject] + Verb (possibly + Object of Verb)
- That is the person who hiccuped.
- That is the person who saw me.
- Relative Pronoun [Functioning as Object of Preposition] + Subject + Verb (possibly + Object of Verb) + Preposition
- That is the person who(m) I was talking about.
- That is the person who(m) I was telling you about.
- Preposition + Relative Pronoun [Functioning as Object of Preposition] + Subject + Verb (possibly + Object of Verb)
- That is the person about whom I was talking.
- That is the person about whom I was telling you.
- Possessive Relative Pronoun + Noun [Functioning as Subject] + Verb (possibly + Object of Verb)
- That is the dog whose big brown eyes pleaded for another cookie.
- That is the dog whose big brown eyes begged me for another cookie.
- Possessive Relative Pronoun + Noun [Functioning as Object of Verb] + Subject + Verb
- That is the person whose car I saw.
For a discussion of adjective clauses in languages other than English, see Relative clause#Examples.
English punctuation 
The punctuation of an adjective clause depends on whether it is essential or nonessential and use commas accordingly. Essential clauses are not set off with commas, while non-essential clauses are. An adjective clause is essential if the information it contains is necessary to the meaning of the sentence. For example:
- The vegetables that people often leave uneaten are usually the most nutritious.
Here "vegetables" is nonspecific. Accordingly, in order to know which ones is being referred to, one must have the information provided in the adjective clause (in italics). Because it restricts the meaning of "vegetable", this adjective clause is called a restrictive clause. It is essential to the meaning of the main clause and uses no commas (and correspondingly, does not experience a pause when spoken).
However, if the additional information does not help to identify more narrowly the identity of the noun antecedent but rather simply provides further information about it, then the adjective clause is non-restrictive and does require commas (or a spoken pause) to separate it from the rest of the sentence. For example:
- Broccoli, which people often leave uneaten, is very nutritious.
Depending on context, a particular noun could be modified by either a restrictive or non-restrictive adjective clause. For example, while "broccoli" is modified non-restrictively in the preceding sentence, it is modified restrictively in the following.
- The broccoli which (or that) people leave uneaten is often nutritious.
Adverbial clause 
"He saw Mary when he was in New York" and "They studied hard because they had a test" both contain adverbial clauses (in italics). Adverbial clauses express when, why, where, opposition, and conditions, As with all dependent clauses, they cannot stand alone. For example, When he was in New York is not a complete sentence; it needs to be completed by an independent clause. For example:
- He went to the Guggenheim Museum when he was in New York.
- When he was in New York, he went to the Guggenheim Museum.
Dependent clauses and sentence structure 
A sentence with an independent clause and one or more dependent clauses is referred to as a complex sentence. One with two or more independent clauses and one or more dependent clauses is referred to as a compound-complex sentence. Here are some English examples:
My sister cried because she scraped her knee. (complex sentence)
- Subjects: My sister, she
- Predicates: cried, scraped her knee
- Subordinating conjunction: because
When they told me (that) I won the contest, I cried, but I didn't faint. **(compound-complex sentence)
- Subjects: they, I, I, I
- Predicates: told me, won the contest, cried, didn't faint
- Subordinating conjunctions: when, that (explicit or understood)
- Coordinating conjunction: but
The above sentence contains two dependent clauses. "When they told me" is one; the other is "(that) I won the contest", which serves as the object of the verb "told." The connecting word "that," if not explicitly included, is understood to implicitly precede "I won" and in either case functions as a subordinating conjunction. This sentence also includes two independent clauses, "I cried" and "I didn't faint," connected by the coordinating conjunction "but." The first dependent clause, together with its object (the second dependent clause), adverbially modifies the verbs of both main clauses.
Non-finite dependent clauses 
Dependent clauses may be headed by an infinitive or other non-finite verb form, which in linguistics is called deranked. In these cases, the subject of the dependent clause may take a non-nominative form. An example is:
- I want him to vanish.
See also 
- Relative pronoun
- Grammatical conjunction
- Subjunctive mood
- Rozakis, Laurie (2003). The Complete Idiot's Guide to Grammar and Style pp. 153–159. Alpha. ISBN 1-59257-115-8.
|Look up dependent clause in Wiktionary, the free dictionary.|
- Owl Online Writing Lab: Independent and Dependent Clauses
- Complex Sentences: Subordinate Clauses as Adverb Clauses