PRESENT PERFECT

Basic Level

http://www.englishexercises.org/makeagame/viewgame.asp?id=9617

http://www.englishexercises.org/makeagame/viewgame.asp?id=2998

http://www.englishexercises.org/makeagame/viewgame.asp?id=5234

http://www.englishexercises.org/makeagame/viewgame.asp?id=2705

Present Perfect VS Past Simple

http://www.perfect-english-grammar.com/present-perfect-exercise-4.html

http://www.englishexercises.org/makeagame/viewgame.asp?id=3365

http://www.englishexercises.org/makeagame/viewgame.asp?id=4426

http://www.flo-joe.co.uk/preliminaryenglish/grammar/present-perfect-or-past-simple.htm

Since or For

http://www.englishexercises.org/makeagame/viewgame.asp?id=1394

http://www.englishlearner.com/intermediate/since-or-for-1.shtml

Already and Yet

http://www.englishlearner.com/intermediate/already-or-yet-1.shtml

PRESENT SIMPLE

PRESENT SIMPLE VS PRESENT CONTINUOUS

http://www.englishexercises.org/makeagame/viewgame.asp?id=2332

http://www.englishexercises.org/makeagame/viewgame.asp?id=5316

http://www.englishexercises.org/makeagame/viewgame.asp?id=5869

http://www.englishexercises.org/makeagame/viewgame.asp?id=1438

http://www.perfect-english-grammar.com/present-simple-present-continuous-1.html

http://www.englishpage.com/verbpage/verbs1.htm

http://www.englishpage.com/verbpage/verbs2.htm