http://www.englishexercises.org/makeagame/viewgame.asp?id=8301
http://www.englishexercises.org/makeagame/viewgame.asp?id=2757
http://www.englishexercises.org/makeagame/viewgame.asp?id=4925
http://www.eclecticenglish.com/grammar/PresentSimpleToBe1B.html
http://www.eclecticenglish.com/grammar/PresentSimpleToBe1C.html