8.9 tenses in time clauses

When you are talking about the past or the present, the verb in a time clause has the same tense that it would have in a main clause or in a simple sentence.

• I was standing by the window when I heard her speak.
• I haven't given him a thing to eat since he arrived.
• I look after the children while she goes to London.

However, if the time clause refers to something that will happen or exist in the future, you use the simple present tense, not a future tense.

For example, you say 'When he comes, I will show him the book', not 'When he will come, I will show him the book'.

• As soon as we get the tickets, we'll send them to you.
• He wants to see you before he dies.
• Let me stay here till Jeannie comes to bed.

If you mention an event in a time clause which will happen before an event referred to in the main clause, you use the present perfect tense in the time clause, not the future perfect tense.

For example, you say 'When you have had your supper, come and see me', not 'When you will have had your supper, come and see me'.

• We won't be getting married until we've saved enough money.
• Tell the DHSS as soon as you have retired.

8.10

The most common conjunction in time clauses is 'when'. 'When' is used to say that something happened, happens, or will happen on a particular occasion.

• When the telegram came and I read of his death, I couldn't believe it.
• He didn't know how to behave when they next met.

8.11

You can mention the circumstances in which something happens or happened by using 'when', 'while', or 'as'.

• The train has automatic doors that only open when the train is stationary.
• While he was still in the stable, there was a loud knock at the front door.
• He would swim beside me as I rowed in the little dinghy.

'Whilst' is a more formal form of 'while'.

• Two were mere lodgers whom we looked after whilst their mistress was away.