exercises in simple present

http://www.ego4u.com/en/cram-up/grammar/simple-present/form/exercises

http://www.englishexercises.org/makeagame/viewgame.asp?id=2272

http://www.englishexercises.org/makeagame/viewgame.asp?id=1925

http://www.learnenglish.be/gr1_prsi_study.htm