Unit 13 Present perfect and past(1)(I have done and I did)
A.Tom is looking for his key.He can't find it.
He has lost his key.
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 hasn't.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 is a present tense.It always tells us something about now. Tom has lost his key=he doesn't have his key now.
The past simple tells us only about the past.If somebody says "Tom lost his key", we don't know whether he has it now or not. We only know that he lost it at some time in the past.
B.Do not use the present perfect if there is no connection with the present(for example, things that happened a long time ago):
*The Chines invented printing.
*Shakespeare wrote many plays.
*My sister is a writer.She has written many books.(she still writes books)
C. We use the present perfect to give new information. But if we continue to talk about it, we normally use the past simple:
*Ow! I've burnt myself.
How did you do that?
I picked up a hot dish.
Look! somebody has spilt milk on the carpet.引自第39页