Para repasar la voz pasiva.

http://www.ego4u.com/en/cram-up/grammar/passive/exercises
http://www.ego4u.com/en/cram-up/grammar/passive/exercises?02
http://www.ego4u.com/en/cram-up/grammar/passive/exercises?simple-present
http://www.ego4u.com/en/cram-up/grammar/passive/exercises?simple-past
http://www.ego4u.com/en/cram-up/grammar/passive/exercises?present-progressive