Past Simple or Present Perfect?

Which is correct and why?

The word yesterday makes all the difference here. It provides a time frame, and that makes all the difference. You can say I have seen him today, but you can't say I have seen him yesterday. I suppose the reason for that is that while saw refers to the past, have seen is about both the past and the present.

How's that?

:wink:

Agreed. ;-)

The reason why I've chosen "saw" is that it's known that you can only use Perfect time when the action is continuing, when it's not finished, no matter whether you use it in the past, in the present or in the future , which I often when happen to have a problem with. But one thing is for sure that there's no way you can use yesterday with Perfect time. But you can use it when talking about today, as the action is not finished yet.

'Yesterday' is finished time, so use the past. 'Today' is different- we use both. ;-)

Quote:

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Originally Posted by tdol

'Yesterday' is finished time, so use the past. 'Today' is different- we use both. ;-)

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What do you mean by saying "we use both"? Oh, I've just remembered that I've happened to come across in the books "yesterday" to be used with the Past Perfect time. Is taht correct? :wink:

I could say 'I haven't had lunch today', unfinished time and I expect to have lunch. If I have left my office and am on the bus home I could say 'I did a lot of work today'. Here, the day has not ended, but the working part has and I don't expect to do any more work.;-)

Quote:

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Originally Posted by tdol

I could say 'I haven't had lunch today', unfished time and I expect to have luch. If I have left my office and am on the bus home I could say 'I did a lot of work today'. Here, the day has not ended, but the working part has and I don't expect to do any more work.;-)

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Ha, at least now I know how to use this form.
So if I understood you right, I can use present perfect for today when there's a possibility for something to happen today again, but when something has been done completely, and you know that it's going to happen for today as well, then you can't use this form.
What will the right thing to say: I've had a great lunchtoday, or: I had a great lunch today (you're not supposed to have another lunch today, maybe dinner only)? :wink:

If the lunch is very recent- for example, you're still in the restaurant or just after, then it has enough present relevance to use the perfect.;-)

How to learn to use Perfect Times correctly? All of Them? Is there a way to it actually?