Present perfect - use in real life:
1. Completed actions with implications in the present.
We must remember that present perfect is a present tense. It can be used to talk about completed action in the past, however:
I've finished my English homework. (Present perfect)
But the person who said this was also implying something which is present. For example, he could be saying
Can I go home now?
Can I do another exercise now?
Can you check it for me , teacher? etc.
If we are thinking about or we mention a past time when we speak, then we can't use present perfect; we use past simple:
I finished my English homework before dinner last night. (Past simple)
2. An action that started in the past and continues in the present.
If a past action continues to the present time, we use present perfect to express that action:
I've had this shirt for two days.
Spain have been world soccer champions for a long time.
Mary has always liked John.
In the above examples we assume that: I have the shirt now; Spain are world soccer champions now; Mary likes John now.
It is a mistake to use present simple in these situations:
I have this shirt for two days.
With this use of present perfect, it is common to use the prepositions "for" and "since" to express how much time has passed. "For" is used to talk about a period of time and "since" is used to mention the starting moment of the action:
I've wanted to own a car like that for years.
He's only known that girl for about two weeks.
There's been a power cut since eight o'clock this morning.
Mary has dressed in that way since she was a teenager.
Present perfect is also used in a similar way to talk about repeated actions in the past but with reference to a present time like: this year, this month, recently, etc:
My husband has been to Madrid three times this year.
I've had a cold twice this month.
There have been several robberies in this area recently.
This second use of present perfect is closely related to present perfect continuous...