ADVERBIAL CLAUSE

An adverbial clause is a dependent clause that functions as an adverb. In other words, it contains a subject (explicit or implied) and a predicate, and it modifies a verb.

• I saw Joe when I went to the store. (explicit subject I)
• He sat quietly in order to appear polite. (implied subject he)

According to Sidney Greenbaum and Randolph Quirk, adverbial clauses function mainly as adjuncts or disjuncts. In these functions they are like adverbial phrases, but due to their potentiality for greater explicitness, they are more often like prepositional phrases (Greenbaum and Quirk,1990):

• We left after the speeches ended. (adverbial clause)
• We left after the end of the speeches. (adverbial prepositional phrase)

Contrast adverbial clauses with adverbial phrases, which do not contain a clause.

• I like to fly kites for fun.

Adverbial clauses modify verbs, adjectives or other adverbs. For example:

• Hardly had I reached the station when the train started to leave the platform.

The adverbial clause in this sentence is "when the train started to leave the platform" because it is a subordinate clause and because it has the trigger word (subordinate conjunction) "when".

Kinds of adverbial clauses

kind of clause	common conjunctions	function	example
time clauses	when, before, after, since, while, as, as long as, until,till, etc. (conjunctions that answer the question "when?"); hardly, scarcely, no sooner, etc.	These clauses are used to say when something happens by referring to a period of time or to another event.	Her goldfish died when she was young.
conditional clauses	if, unless, lest	These clauses are used to talk about a possible or counterfactual situation and its consequences.	If they lose weight during an illness, they soon regain it afterwards.
purpose clauses	in order to, so that, in order that	These clauses are used to indicate the purpose of an action.	They had to take some of his land so that they could extend the churchyard.
reason clauses	because, since, as, given	These clauses are used to indicate the reason for something.	I couldn't feel anger against him because I liked him too much.
result clauses	so...that	These clauses are used to indicate the result of something.	My suitcase had become so damaged on the journey home that the lid would not stay closed.
concessive clauses	although, though, while	These clauses are used to 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 clauses	where, wherever, anywhere, everywhere, etc. (conjunctions that answer the question "where?")	These clauses are used to talk about the location or position of something.	He said he was happy where he was.
clauses of manner	as, like, the way	These clauses are used to talk about someone's behaviour or the way something is done.	I was never allowed to do things as I wanted to do them.

Sumber:  http://en.wikipedia.org/wiki/Adverbial_clause