Passive Voice

http://www.english-zone.com/verbs/pssvchrt.html

http://esl.about.com/library/grammar/blpassive.htm

Exercises:

http://www.englisch-hilfen.de/en/exercises_list/passiv.htm

http://english-zone.com/verbs/passive8.html

http://esl.about.com/library/quiz/blgrquiz_passive1.htm

http://a4esl.org/q/h/vm/active-passive.html