http://perso.wanadoo.es/autoenglish/gr.pas.i.htm
http://www.perfect-english-grammar.com/passive-exercise-1.html
http://www.perfect-english-grammar.com/passive-exercise-2.html
http://www.english-4u.de/passive_ex1.htm
http://www.englishexercises.org/makeagame/viewgame.asp?id=1373
http://www.englishexercises.org/makeagame/viewgame.asp?id=7324
http://www.englishexercises.org/makeagame/viewgame.asp?id=1609
http://www.englishexercises.org/makeagame/viewgame.asp?id=1870
http://www.englishexercises.org/makeagame/viewgame.asp?id=3340
http://www.englishexercises.org/makeagame/viewgame.asp?id=8086
http://www.englishexercises.org/makeagame/viewgame.asp?id=10898
http://www.englishexercises.org/makeagame/viewgame.asp?id=55