FORM
[has/have + past participle]

The present perfect is a grammatical combination of the present tense and the perfect aspect, used to express a past event that has present consequences.

The present perfect in English is used chiefly for completed past actions or events, when it is understood that it is the present result of the events that is focused upon, rather than the moment of completion.

i.e I have [present tense] eaten [perfect aspect]; he has eaten (present perfect, generally denoting something that took place prior to the present moment)

1) Actions started in the past and continuing in the present:

We have had the same car for eleven years.

2) When the time period referred to has not finished:

It has rained a lot this year.

3) Actions repeated in an unspecified period between the past and now:

We have eaten at that restaurant many times.

4) Actions completed in the very recent past (+just):

Have you just finished work?

5) When the precise time of the action is not important or not known:

She’s studied Japanese, Russian and English.

Unspecified time before Now

• I have seen that movie twenty times.
• I think I have met him once before.
• There have been many earthquakes in California.
• People have traveled to the Moon.
• People have not traveled to Mars.
• Have you read the book yet?
• Nobody has ever climbed that mountain.
• A: Has there ever been a war in the United States?
• B: Yes, there has been a war in the United States.