Past Simple or Present Perfect (2); ago, for, since
Compare the Past Simple and the Present Perfect:
|Past Simple||Present Perfect|
|Look at this example of the Past Simple:
There were many earthquakes last century.
Note that last century is a period of past time. It ended before now.
|Look at this example of the Present Perfect:
There have been many earthquakes this century.
Note that this century is a period of time that includes now (the time of speaking).
|We use the Past Simple to talk about events or situations in a period of past time:
A: How long did you work in your last job?
B: I worked there for four years.
Sheila did not go to work yesterday.
We use the Past Simple for events in the lifetime of someone who is dead:
A: Did your grandmother ever visit Canada?
B: Yes, she spent several holidays there.
|We use the Present Perfect for events or situations in a period of time that includes now:
A: How long have you worked here?
B: I've worked here since last summer. (I still work here).
Have you been to the cinema this week?
Sheila has not gone to work today.
We use the Present Perfect for events in the lifetime of a living person:
A: Have you ever visited Canada?
B: Yes, I've had several holidays there.
Notice how a sentence with the Past Simple and one with the Present Perfect can give similar information from different points of view. Notice the use of ago, for and since:
|Pam went to live in Dublin 5years ago.||Pam has lived in Dublin for five years. Pam has lived in Dublin since her wedding, (or... since she got married).|
Present Perfect and Past (1) (I have done and I did)
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 (Present Perfect)?
No, he hasn't. He has found it.
Did he lose his key (Past Simple)? 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.
Two more examples:
- Jack 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 writer. She has written many books (she still writes books).
We use the Present Perfect to give new information. But if we continue to talk about it, we normally use the Past Simple:
- A: Oh! 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 milk on the carpet.
B: Well, it wasn't me. I didn't do it (not hasn't been...haven't done).
A: I wonder who it was then (not who it has been).
Do not use the Present Perfect (I have done) when you talk about a finished time (for example, yesterday, ten minutes ago, in 1985, when I was a child). Use a past tense:
- The weather was nice yesterday (not has been nice).
- They arrived ten minutes ago (not have arrived).
- I ate a lot of sweets when I was a child (not have eaten).
- A: Did you see the news on television last night (not Have you seen)?
B: No, I went to bed early (not have gone).
Use a past tense to ask When... or What time...:
- When did they arrive (not have they arrived)?
- What time did you finish work?
- Present Perfect
- Tom has lost his key. He can't get into the house.
Here, we are not thinking of the past action. We are thinking of the present result of the action: Tom doesn't have his key now.
- Tom lost his key yesterday. He couldn't get into the house.
Here, we are thinking of the action in the past. We don't know from this sentence whether Tom has his key now.
Compare Present Perfect and Past Simple:
- Present Perfect (have done)
- I've done a lot of work today.
We use the Present Perfect for a period of time that continues from the past until now. For example, today, this week, since 1985.
- It hasn't rained this week.
- Have you seen Ann this morning (it is still morning)?
- Have you seen Ann recently?
- I don't know where Ann is. I haven't seen her(=I haven't seen her recently).
- We've been waiting for an hour (we are still waiting now).
- Tom lives in London. He has lived there for seven years.
- I have never played golf (in my life).
The Present Perfect always has a connection with now.
- Past Simple (did)
- I did a lot of work yesterday.
We use the past simple for a finished time in the past. For example, yesterday, last week, from 1985 to 1991.
- It didn't rain last week.
- Did you see Ann this morning (it is now afternoon or evening)?
- Did you see Ann on Sunday?
- A: Was Ann at the party on Sunday?
B: I don't think so. I didn't see her.
- We waited (or were waiting) for an hour (we are no longer waiting).
- Lan lived in Scotland for ten years. Now he lives in London.
- I didn't play golf when I was on holiday last summer.
The past simple tells us only about the past.