Study this example situation:
Ann is looking for her key. She can’t find it.
She has lost her key. (present perfect)
This means that she doesn’t have her key now.
Twenty minutes later:
Now Ann has found her key. She has it now.
Has she lost her key? (present perfect)
No, she hasn’t. She has found it.
Did she lose her key? (past simple)
Yes, she did.
She lost her key (past simple)
but now she has found it. (present perfect)
The present perfect is a present tense. It always tells us something about now. “Ann has lost her key” = she doesn’t have her key now (see English Grammar – Present Perfect – Part 1).
The past simple tells us only about the past. If somebody says “Ann lost her key”, we don’t know whether she has it now or not. We only know that she lost it at some time in the past.
Two more examples:
- Paul grew a beard but now he has shaved it off. (so he doesn’t have a beard now)
- They went out after lunch and they’ve just come back. (so they are back now)
Do not use the present perfect if there is no connection with the present (for example, things that happened a long time ago):
- The Chinese invented printing. (not “have invented”)
- How many plays did Shakespeare write? (not “has Shakespeare written”)
- Beethoven was a great composer. (not “has been”)
- Shakespeare wrote many plays.
- My sister is a young writer. She has written many books. (she still writes books)
We use the present perfect to give new information (see English Grammar – Present Perfect – Part 1). But if we continue to talk about it, we normally use the past simple:
Ow! I’ve burnt myself.
How did you do that? (not “have you done”)
I picked up a hot dish. (not “have picked”)
Look! Somebody has spilt milk on the carpet.
Well, it wasn’t me. I didn’t do it. (not “hasn’t been…haven’t done”)
I wonder who it was then. (not “who it has been”)