http://www.englishgrammarsecrets.com/passive/exercise3.swf
http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-28628.php
http://www.english-grammar-lessons.com/passive/exercise2.swf
http://www.esl-lounge.com/student/grammar/3g22-passive-present-exercise.php
http://www.esl-lounge.com/student/grammar/3g20-passive-active-exercise.php

http://quizlet.com/26166311/new