Adverbial clause
An adverbial clause is a dependent clause that functions as an adverb; that is, the entire clause modifies a verb, an adjective, or another adverb. As with all clauses, it contains a subject and predicate, although the subject as well as the (predicate) verb may sometimes be omitted and implied (see below).
An adverbial clause is commonly, but not always, fronted by a subordinate conjunction—sometimes called a trigger word. (In the examples below the adverbial clause is italicized and the subordinate conjunction is bolded.)
- Mary, the aspiring actress, became upset as soon as she saw the casting list.
- (subject: she; predicate: saw the casting list; the clause modifies the verb became)
 
- Peter Paul, the drama teacher, met with Mary after she came to the next class.
- (explicit subject: she; predicate: came to the next class.; predicate (verb): came; the clause modifies the verb met;)
 
- He talked carefully in order to appear fair.
- He talked carefully in order .. [that 'he'] appear fair.
- (implied subject, he, is omitted; predicate (verb): appear; the clause modifies the adverb carefully)
 
- The little boy preferred fierce dinosaurs, as T rex.
- The little boy preferred fierce dinosaurs, as [was] T rex.
- (subject of the clause: T rex; predicate of the clause: [was], implied; the clause modifies the adjective fierce.)
 
According to Sidney Greenbaum and Randolph Quirk, adverbial clauses function mainly as adjuncts or disjuncts, which parts also perform in a sentence as adverbial phrases or as adverbial prepositional phrases (Greenbaum and Quirk,1990). Unlike clauses, phrases do not contain a subject and predicate; they are contrasted here:
- We left the convention the day before.
- (adverbial phrase; contains no subject or predicate)
 
- We left before the speeches.
- (adverbial prepositional phrase; contains no subject or predicate—and no verb (action) is implied)
 
- We left after the speeches ended.
- (adverbial clause; contains subject and predicate)
 
- We left after the speeches.
- or, (".. after the speeches [ended]")
- (adverbial clause; contains subject and predicate, but the verb 'ended' is omitted and implied)
 
Types
Adverbial clauses are divided into several groups according to the actions or senses of their conjunctions:
| Type of clause | Common conjunctions | Function | Example | 
| time | Conjunctions answering the question "when?", such as: when, before, after, since, while, as, as long as, till, until, etc.; or the paired (correlative) conjunctions: hardly...when, scarcely...when, barely...when, no sooner...than[1] | These clauses: Say when something happens by referring to a period or point of time, or to another event. | Her goldfish died when she was young. He came after night had fallen. We barely had gotten there when mighty Casey struck out. | 
| condition | if, unless, lest | Talk about a possible or counterfactual situation and its consequences. | If they lose weight during an illness, they soon regain it afterwards. | 
| purpose | in order to, so that, in order that | Indicate the purpose of an action. | They had to take some of his land so that they could extend the chuchyard. | 
| reason | because, since, as, given | Indicate the reason for something. | I couldn't feel anger against him because I liked him too much. | 
| concession | although, though, while | Make two statements, one of which contrasts with the other or makes it seem surprising. | I used to read a lot although I don't get much time for books now. | 
| place | Answering the question "where?": where, wherever, anywhere, everywhere, etc. | Talk about the location or position of something. | He said he was happy where he was. | 
| comparison | as...as, than, as | State comparison of a skill, size or amount, etc. | Johan can speak English as fluently as his teacher. She is a better cook than I. | 
| manner | Answering the question, "how"?: as, like, the way | Talk about someone's behavior or the way something is done. | I was never allowed to do things as I wanted to do them. | 
| results | so...that, such...that | Indicate the result(s) of an act or event. | My suitcase had become so damaged that the lid would not stay closed. | 
References
Further reading
- Greenbaum, Sidney & Quirk, Randolph. A Student's Grammar of the English Language. Hong Kong: Longman Group (FE) Ltd, 1990.
- Sinclair, John (editor-in-chief). Collins Cobuild English Grammar. London and Glasgow: William Collins Sons & Co ltd, 1990.