9th year - Present Perfect vs Past Simple

These are both tenses that deal with past actions. That's why sometimes is hard to distinguish.
The difference is that Past Simple is for actions that took place and finished in the past. And Present Perfect is for actions that took place in an indetermined time in the past.

Confused?!?

The best way is to answer to some exercises!

First - pages 28/29 from your book (exercises 1,2,3 and 4)

second - http://web2.uvcs.uvic.ca/elc/StudyZone/410/grammar/ppvpast2.htm