I have eaten lunch

Mr.P. - Before this thread, would you have thought there could be a sentence that would be grammatically correct ONLY if spoken in the morning? Well, here it is - as you have already pointed out, you can correctly say "Have you seen him this morning" only if it's still morning. If you say it in the afternoon, it's ungrammatical!

So, getting back to Temico's post questioning the difference between "Have you seen my pencil this morning?" and "Have you seen my pencil yesterday?" -- You can say "have you seen my pencil this morning?" because you can ask the question WHILE IT'S STILL THIS MORNING, but unless you have a time machine, you can't ask "Have you seen my pencil yesterday?" while it's still yesterday.

By the way, there was a Time Traveller's Convention last week at M.I.T. -- you can still go, if you qualify!

I love this board.

-khoff

when translated into foreign(not related to Latin) languages, "Did you see..." and "Have you seen...." are EXACTLY the same.

Indeed, temcio. However, that is one of the mysteries of learning a foreign language - it is different from your native language!

Anybody can TRUTHFULLY answer, "No, I have not." even if s/he has seen Tom pass by ONE MINUTE/SECOND ago!!

Of course they can. But they can't say "I haven't seen Tom pass by yesterday

It would have to be "I didn't see Tom .... yesterday"

Michael Swan - Practical English Usage

419-3 Grammars usually say that the present perfect cannot be used together with expressions of finished time. ... In fact, such structures are unusual but not impossible (though learners should avoid them).

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CGEL:
Past time adjuncts in experential perfects

This use of the present perfect allows for the inclusion, under restrictive conditions, of a past time adjunct:

[13]

i. a. He has got up at five o'clock. b. He got up at five o'clock.
ii. a. We've already discussed this yesterday. b. We discussed this yesterday.

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JTT:

In the newspaper, just a few weeks ago, Tony Blair, in reference to the WMDs stated,

"I've already discussed that last year."

ENLs NORMALLY, ALMOST NEVER use the present perfect with past time adjuncts. There are a few exceptions as noted by Swan and the CGEL.

Please let me cut in again! Just to cite a data.

McCoard(1978:135) gives a list of adverbials he finds to belong in each of these following three classes:

#1. Occur with simple past but not with perfect:
long ago, five years ago, once(=formerly), the other day, those days, last night, in 1990, at 3:00, after the war, no longer.

#2. Occur with either simple past or with perfect:
long since, in the past, once(=one time), today, in my life, for three years, recently, just now, often, always, never, already, before.

#3. Occur with perfect but not with simple past:
at present, up till now, so far, as yet, during these last five years, herewith, lately, since the war, before now, by now.

I found it in Dowty1991:341. Is this list reliable...? Anyway, this thread is interesting. I'm all ears.