Para Nico

http://www.ego4u.com/en/cram-up/grammar/passive/exercises?future-1
http://www.ego4u.com/en/cram-up/grammar/passive
http://www.saberingles.com.ar/curso/lesson24/06.html
http://www.agendaweb.org/verbs/passive-exercises.html
http://www.myenglishpages.com/site_php_files/grammar-exercise-passive.php#.VGut1PmG_wg
http://www.e-grammar.org/passive-voice/