# Thread: I have used the computer for two hours.

1. ## I have used the computer for two hours.

Hello, I want to ask a question about the difference between present perfect and present perfect continuous.

Are the below sentences OK?

1. I have used the computer for two hours.
2. I have studied English since this morning.
3. I have read the book for five hours.

It seems better to use present perfect continuous instead. But are the above sentences plain wrong?

2. ## Re: I have used the computer for two hours.

I have been using the computer for two hours.
I have been studying english since this morning.
I have been reading the book for five hours.

How long did you use the computer?
I used the computer for two hours.

How long have you been studying English?
Since this morning.

How long have you been reading the book?
I have been reading it for five hours.

Hope this helps,
Joany

3. ## Re: I have used the computer for two hours.

Originally Posted by Yoshio
It seems better to use present perfect continuous instead. But are the above sentences plain wrong?

No, they're not. We use the present perfect continuous when we want to stress the duration or the fact that the action is unfinished. We can use the simple form when the action hasn't finished; it's more a question of how important it is to tell the listener that it's not finished or the length of time.

4. ## Re: I have used the computer for two hours.

I read Joany's example sentences and Tdol's explanation on the use of present perfect simple and present perfect continuous. I suppose I understand it. But I came up with some other questions.

Can I use the simple form no matter how short the length of time is, as long as the action hasn't finished?

The continuous form seems to be often used when the time of duration is short. Then what if the time is very long, like a century or more.

5. ## Re: I have used the computer for two hours.

The continuous can be used used to emphasise the duration:
I've been waiting for over an hour!
Here, the waiting has finished (if they are speaking to the person who has kept them waiting), but the speaker wants to emphasise the considerable length of time. It can emphasise length in both directions- 'I've been living here for three weeks' (short time or temporary).

Can I use the simple form no matter how short the length of time is, as long as the action hasn't finished?
The simple form can be used for finished and unfinished actions; the most important factor is that the action has some relevance to the present time.

6. ## Re: I have used the computer for two hours.

Thank you, Tdol.

Your explanation is very clear and I think I understand it.

7. ## Re: I have used the computer for two hours.

Yoshio, you're welcome. I am afraid that the uses are not easy to distill into simple rules.

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