what is the use of the present perfect?

1. PRESENT PERFECT

2. USE

3. To talk about changes that has
happened over a period of time
You have grown since the last time I saw you
The goverment has invested more in arts for the three last
years.
My english has improved since I moved to Australia.

4. expressions
FOR + a period of time
For six years, for a week, for a month.
SINCE + a point in time
Since this morning, since last year, since yesterday

5. STRUCTURE

6. AFFIRMATIVE FORM:
SUBJECT AUX VERB (past participle) COMPLEMENT
We have climbed Valle de los Halcones
My father has prepared My fifteen party
The auxiliars are:
HAVE I, WE, YOU, THEY
HAS HE, SHE, IT

7. NEGATIVE FORM:
SUBJECT AUX N`T VERB
(past participle)
COMPLEMENT
We have n´t diven in the ocean
My father has n´t bought A bike

8. INTERROGATIVE FORM:
yes-no questions
AUX SUBJECT VERB
(past participle)
COMPLEMENT ?
have you prepared sushi?
has Your father driven a motorbike?

9. ANSWERS
LONG:
Yes, we have prepared sushi.
No, he hasn`t driven a motorbike.
SHORT:
Yes, we have.
No, he hasn`t

10. INTERROGATIVE FORM:
wh questions
wh AUX SUBJECT VERB
(past
participle)
COMPLEMENT
when have you sailed The boat?
where has Your mother bought The farm?