Time clauses

When

He was talking on the phone when I arrived.
When she called, he had already eaten lunch.
I washed the dishes when my daughter fell asleep.
We'll go to lunch when you come to visit.

Before

We will finish before he arrives.
She (had) left before I telephoned.

After

We will finish after he comes.
She ate after I (had) left.

While

She began cooking while I was finishing my homework.

As

As I was finishing my homework, she began cooking.

By the time

By the time he finished, I had cooked dinner.
We will have finished our homework by the time they arrive.

Until

We waited until he finished his homework.

Till

I'll wait till you finish.

Since

I have played tennis since I was a young boy.

As soon as

He will let us know as soon as he decides.
He will let us know as soon as he has decided.

參考
http://esl.about.com/library/grammar/blgr_adverbclauses_time.htm