www.agendaweb.org/verbs/passive-exercises.html
www.englisch-hilfen.de/en/exercises_list/passiv.htm
www.myenglishpages.com/site_php_files/grammar-exercise-passive.php
www.eslgamesplus.com/passive-voice-past-passive-esl-grammar-sentence-activity-fun-game-online/
www.eslgamesplus.com/whats-it-made-of-passive-voice-product-materials-esl-hangman/ šibenice