Hi, guys! Below, you'll find some links to revise for the exam as well as an explanation about the differences in use between Present Perfect and Simple Past.
1. Explanation Present Perfect vs Simple Past. It's very clear!
2. Do the following activities on present pervect vs simple past
http://www.ego4u.com/en/cram-up/grammar/simpas-preper
http://www.usingenglish.com/quizzes/228.html
3. Do the following activities on yet & already and for & since
4. Take a break! Revise some past participles doing the following crossword.
