Adverbial Clauses

An adverb may be a single word such as quickly, here or yesterday (see the page Adverbs), or a phrase such as the day before yesterday or to see my mother (see the page Adverb Phrases). However, adverbs can also be clauses, containing a subject and a full verb. This page will explain the basic types of adverb clauses (sometimes called "adverbial clauses") and how to recognize them.

Adverbs, adverb phrases, and adverb clauses

Look at these sentences:

I saw the movie yesterday.

I saw the movie on Friday.

I saw the movie before I left for Calgary.

In the first sentence, “yesterday” is a one-word adverb, “on Friday” is an adverb phrase, and “before I left for Calgary” is an adverb clause. All of them answer the question “When?”, but the adverb clause has a subject (“I”) and a full verb (“left”). It is introduced by “before”, so it is a dependent clause. This means that it cannot stand alone: “Before I left for Calgary” would not be a full sentence. It needs a main clause (“I saw the movie”). An adverb clause, then, is a dependent clause that does the same job as an adverb or an adverb phrase.

Types of adverb clause

There are many types of adverb clauses. Here are some examples of the most common types:

Type	Question answered	Example
Place	Where?	Wherever there are computers, there is Microsoft software.
Time	When?	After the fruit is harvested, it is sold at the market.
Cause	Why? (What caused this?)	I didn't call her because I'm shy.
Purpose	Why? (What was the reason for doing this?)	She took a computer course so that she could get a better job.
Concession	Why is this unexpected?	Although Jay has a Master's degree, he works as a store clerk.
Condition	Under what conditions?	If you save your money, you will be able to go to college.

As you can see from the examples above, most adverb clauses can be recognized because they are introduced by a particular word or phrase (such as "when" and "so that"). These words and phrases are called subordinating conjunctions, and there are many of them, including these:

after, before, until, while, because, since, as, so that, in order that, if, unless, whether, though, although, even though, where.

sumber :

http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/advcls.htm