Page 38 - English Grammar in Use

Unit
13 Present perfect and past 1 (I have done and I did)

A Study this example situation:
Tom is looking for his key. He can’t find it.
He has lost his key. (present perfect)
This means that he doesn’t have his key now.

Ten minutes later:
Now Tom has found his key. He has it now.
Has he lost his key? No, he has found it.
Did he lose his key? Yes, he did.
He lost his key (past simple)
but now he has found it. (present perfect)

The present perfect (something has happened) is a present tense. It tells us about the situation now.
‘Tom has lost his key’ = he doesn’t have his key now (see Unit 7).

The past simple (something happened) tells us only about the past. If somebody says ‘Tom lost his key’,
we don’t know whether he has the key now or not. We know only that he lost it at some time in the past.
Compare present perfect and past simple:
They’ve gone away. They’ll be back on Friday. (they are away now)
They went away, but I think they’re back at home now. (not They’ve gone away)
It has stopped raining now, so we don’t need the umbrella. (it isn’t raining now)
It stopped raining for a while, but now it’s raining again. (not It has stopped)

B You can use the present perfect for new or recent happenings:
I’ve repaired the washing machine. It’s working OK now.
‘Hannah has had a baby! It’s a boy.’ ‘That’s great news.’
Usually, you can also use the past simple:
I repaired the washing machine. It’s working OK now.
Use the past simple (not the present perfect) for things that are not recent or new:
Mozart was a composer. He wrote more than 600 pieces of music.
(not has been … has written)
My mother grew up in Italy. (not has grown)
Compare:
Somebody has invented a new type of washing machine.
Who invented the telephone? (not has invented)

C We use the present perfect to give new information (see Unit 7). But if we continue to talk about it,
we normally use the past simple:
a: Ow! I’ve burnt myself.
b: How did you do that? (not have you done)
a: I picked up a hot dish. (not have picked)
a: Look! Somebody has spilt something on the sofa.
b: Well, it wasn’t me. I didn’t do it. (not hasn’t been … haven’t done)

Past simple ➜ Unit 5 Present perfect ➜ Units 7–8 Present perfect and past 2 ➜ Unit 14
26 American English ➜ Appendix 7