Verbs
Present perfect vs. past simple
The present perfect is used to talk about:
 -situations which started in the past and continue now.
  -  I have lived in Japan for 13 years.
-  She has worked as a teacher for two months.
-experiences at an indefinite time in the past.
  -  I've been to Rome, but I've never been
    to Venice.
-  Have you seen the new Woody Allen film?
		
When the situation is finished, we use the past
  simple.
	-  I have collected thousands of stamps.
		= I collect stamps now.
-  I collected stamps when I was a child. =
		I don't collect stamps anymore.
 NOT:  I have collected stamps when I was a child.
When we are speaking about a completed experience at a specific time,
  we use the past simple. Compare these sentences:
  -  I've read Gone with the Wind.
    (when is not specified)
-  I read Gone with the Wind when I
    was 15. (when is specified)
 NOT:  I've read Gone with the Wind when
    I was 15.