We use the Present Perfect to refer to an action that happened at an unspecified time before now.

• We use Present Perfect to express an action that is still going on or that stopped recently, but has an influence on the present.
  

         - I have seen three movies this week. (This week hasn't finished yet)
         - Gerry has failed his exam again. (Time is not mentioned)
         - The football player has just scored a goal (Time is recent)

• We CAN use the Present Perfect with unspecific time expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.

         - I have seen that movie twenty times.
        - I think I have met him once before.
        - People have travelled to the Moon several times.
        - The army has already attacked that city five times.
        - People have not travelled to Mars yet.
        - Have you ever been to China?
        - I have never studied Chinese

• We use the Present Perfect to show that something started in the past and has continued up until now. We use the expressions SINCE and FOR.
               FOR is used to specify the span or period of time.                              -  She has been in England FOR six months. (In December)
  

                       SINCE is used to specify the point when this period started.
                       -  She has been in England SINCE June.

• We can also use Present Perfect with the following expressions: 

                 ALREADY: It is used  when something has happened earlier than expected. It is placed before the past participle of the main verb.
               - You don't need to feed the dog, I've already done it.

                  JUST: It is used for something that happened very recently. It is placed before the past participle of the main verb.
               - We have just bought a new car.

                 STILL: It is used to emphasize continuing situations. It is placed before the auxiliary verb.
               - I still haven't read the book for the test.

                 YET: It is used to ask if something expected has happened or to say that something expected hasn't happened. It is placed at the end of the sentence.
               - Has the postman arrived yet?
               - My parents haven't arrived yet. (My parents still haven't arrived)

• We CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. THESE EXPRESSIONS ARE USED WITH SIMPLE PAST
  

Structure - Form

We form Present perfect with the Present form of the verb TO HAVE and the Past Participle of the main verb.


For IRREGULAR verbs Past Participles check the LIST in the BLUE LINKS below (most common irregular verbs). For Regular verbs spelling review rules in the article on Simple Past.

If you need any further revision or practice in Present Perfect, use the RED links below.