PRESENT PERFECT AND PAST SIMPLE

If you need more pratice , these websites will be very useful for you.

Grammar & practice :

http://www.ego4u.com/en/cram-up/grammar/simpas-preper

http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/ppvpast.htm

http://www.esltower.com/GRAMMARQUIZ/intermediate/present%20perfect%20vs%20past%202.htm

Practice:

http://www.englishgrammarsecrets.com/presentperfectorpastsimple/exercise1.swf

http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/upperf2.htm

http://perso.wanadoo.es/autoenglish/gr.perf.i.htm

http://www.usingenglish.com/quizzes/228.html

http://www.englishgrammarsecrets.com/presentperfectorpastsimple/exercise3.swf

Yet , already, just, for & since practice:

http://www.englishexercises.org/makeagame/viewgame.asp?id=877

http://www.servator.cat/eva/index_files/Grammar/2ndcycle/4tESO/prsperf2.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=3211

http://www.imparareinglese.co.uk/esercizi_inglese/present_perfect_words.html