Present Perfect Tense

What is Present Perfect Tense? How is it Used?

1. Present perfect tense is used to talk about something that happened at an unspecified time before now.
eg:
He has died.

2. In Present perfect tense, specific time expressions such as, last night, last month, yesterday, a few day ago, etc. can never be used. But you can use, in the last month, in the last week, in the last year, etc.
eg:
I have watched the movie in the last month.
I have met him last week.

3. Unspecified expressions such as, yet, before, twice, onece, etc. can be used in Present perfect tense.
eg:
I have seen him before.
I haven't finished my work yet.
I have read the book once.

4. Present perfect tense is also used to talk about your experience.
eg:
I have been to London.
I have never traveled by plane.

5. Present perfect tense is used to talk about changes that happened over a period of time.
eg:
Your Urdu has really improved since you moved here.
I have become a doctor.

6. Present perfect tense is used to talk about achievements of individuals or humanity.
eg:
Man has walked on the moon.
The child has learn to read.

7. Present perfect tense is used to talk about actions that happened again and again in the past, and are expected to happen again in the future.
eg:
He has failed two times. (maybe, he'll fail again)
He have called him twice. (maybe, he'll call him again)

8. In Present perfect tense, it is not necessary that the action we are talking about finished sometime before now, maybe it finished last month, last year, etc.
eg:
He has died! Don't blame him again and again.
I has resigned. I cannot be held responsible for this.

9. In Present Perfect tense time duration, such as for 2 days, since morning, etc.
eg:
I have known him since 1990.
I have cold for 2 days.