[Grammar] present perfect in interrogative

Why do we use present perfect tense in these senteces?
For example if somebody checks if something is done they say:Have you finished/done it.
or if someone checks if anybody saw someone they say:Have you seen him
or if someone asks another one if they did something they say:Have you tried....?
We expect someone to do something and when we ask them if they did it we ask as:Have you done it?
Why is that so?
Why do we use present perfect here and not past simple.please explain it to me?

egerol1 said:

Why do we use present perfect tense in these senteces?
For example if somebody checks if something is done they say:Have you finished/done it.
or if someone checks if anybody saw someone they say:Have you seen him
or if someone asks another one if they did something they say:Have you tried....?
We expect someone to do something and when we ask them if they did it we ask as:Have you done it?
Why is that so?
Why do we use present perfect here and not past simple.please explain it to me?

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***** NOT A TEACHER *****


Egerol,


(1) What a great question!

(2) I think that it has to do with the nature of the present perfect

vs. the past.

I have lived here for 20 years. = started in the past and still

"touches" the present time. I still live here.

I lived there for 20 years. = I no longer live there.

(3) "Have you eaten breakfast yet?" You would ask this question of

a friend before noon or midday. The idea still "touches" the present time.

(4) "Did you eat breakfast today?" You would ask this question after

midday or noon -- because (in theory) the time for breakfast no longer

exists. The idea of "breakfast" is something in the past.

(5) Therefore, at school, maybe the teacher might ask:

"Have you finished the test yet?" There is still 15 minutes

for the students to work on the test, but the teacher sees that you are

just sitting there. So the teacher does not know whether you have

finished the test or you are thinking about one of the questions. You

might answer: "No, ma'am, I haven't."

(6) When you return home, you tell your family that the test was very

long. So a family member says: "You say that it was very long and that

the students had only one hour to work on it. Did you finish it?" You

answer, "Yes, I did."