Quizzes on Passive and Passive Modals

http://utminers.utep.edu/micontreras/passive.html
http://www.esl-classroom.com/grammar/passive6.html

More on modals
http://www3.telus.net/linguisticsissues/Modals.htm#may

Information on "get"
http://www.grammar-quizzes.com/passive2.html