1. Adverbial clauses of time

An adverbial clause of time shows the time of the action expressed in the principal clause. Time clauses are introduced by after, as, as long as, as soon as, for, just as, once, since, before, by the time (= before, not later than), when, while, until/till (= up to the time when), the moment (that), whenever, every time, immediately, the first time, the last time, the next time etc.:

George had to wait for half an hour before the doctor came.

Time clauses follow the rule of the sequence of tenses; that is, when the verb of the main clause is in a present or future form, the verb of the time clause is in a present form and when the verb of the main clause is in a past form, the verb of the time clause is in a past form too:

I’ll stay in the office until I finish the project.

She arrived before the clock struck nine.

When the time clause precedes the main clause, a comma is used. When the time clause follows, no comma is used:

When he was in Washington, he met the President.

He met the President when he was in Washington.

2. Adverbial clauses of place

An adverbial clause of place shows the place of the action expressed in the principal clause. Adverbial clauses of place are introduced by the conjunctions where and wherever, anywhere, everywhere:

I am quite comfortable where I am.

Deronda placed himself where he could see her.

3. Adverbial clauses of cause (reason)

An adverbial clause of cause (reason) shows the cause of the action expressed in the principal clause. Clauses of reason are introduced by: as, since (= because), because, for (= because), as long (= because), for the reason that, on the grounds that:

She didn't come on time because she was held up in a traffic jam.

When the clause of reason precedes the main clause, we separate the two clauses with a comma:

Since she isn't at home, we'll go out without her.

4. Adverbial clauses of purpose

Adverbial clauses of purpose state the purpose of the action expressed in the principal clause. They are introduced by the conjunctions that, in order that, so that, lest, in case, for fear (that) and some others:

We’ve arrived early so that we may/can/will get a good view of the procession.

I arrived early so that I might not miss anything.

5. Adverbial clauses of manner

Adverbial clauses of manner characterize in a general way the action expressed in the principal clause. They can be introduced by the conjunctions as, in the way (that), as if, as though:

Type this again as I showed you a moment ago.

She acted as if she were mad.

6. Adverbial clauses of comparison

Adverbial clauses of comparison denote an action with which the action of the principal clause is compared. They are introduced by the conjunctions than, as, as…as, not so…as, as if, as though:

We were going up the road as fast as we could.

7. Adverbial clauses of condition

Adverbial clauses of condition state the condition which is necessary for the realization of the action expressed in the principal clause. They are can be introduced by the conjunctions if, as long as, assuming (that), even if, if only, on the condition that, so long as, provided/providing (that), unless:

He’ll definitely win, even if he falls ill.

Suppose/supposing (that) we miss the train, what shall we do?

Unless the management improve their offer, there’ll be a strike.