PRESENT PERFECT 

FORM:(has /have +past participle)

EXAMPLES:

• You have seeb that movie many times
• Have you seen that movie many times?
• You have not seen that movie many times

1. We use the present perfect to say that an action happened at an uspecified time before now.
2. The exact time is not important
3. You can´t use the present perfect with specific time expressions sush as:yesterday , one year ago,last week,when i was a child.when i lived in japan , at that moment,that.

We can use the present perfect with : unspecific expressions,unspecific time such as :ever,never,once,many times,several times,before,so far,already,yet,etc
PAST               PRESENT                      FUTURE

EXAMPLES:

• 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