Chapter time clauses & conditionals unit 15 time clauses

CHAPTER 4. TIME CLAUSES & CONDITIONALS
UNIT 15 TIME CLAUSES

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  Clauses are similar to sentences – they both have the subject and the verb. But they have one difference. Sentences have complete idea but clauses have complete idea:
  

Do you know Ann? (sentence)
Do you know the girl? (clause – because we have know idea which girl)

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  Usually two clauses make one sentence. There is always one main clause and one helping clause:
  

Do you know the girl who is sitting on the left?
Do you know the girl- is a main clause.
who is sitting on the left- is a relative clause.

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  Time clauses show the time when the action happens in the main clause:
  

When I go to Tashkent, I will call you.

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  Time clauses always start with time conjunctions:
  

when while after before as soon as until/till
While I was in Italy I lived with my aunt.

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  A sentence can be started either with the time clause or with the main clause. If we start with the time clause we have to put a comma as there is nothing between the two clauses. But if we start with the main clause we don’t need a comma as there is a time conjunction between the two clauses to link them:
  

As soon as you have done your homework, you can go out.
You can go out as soon as you have done your homework.

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  When we talk about future we use present tense, usually present simple in the time clause, in the main clause we use future forms. If we want to show that the action will be finished we can also use present perfect in the time clause:
  

I’ll do my homework when I go home.
I’ll do my homework when I have repaired my computer.