Unit+2

In the first link you will find some information about the passive voice transformation, tenses, etc., and also some exercises. The others are all exercises http://esl.about.com/library/grammar/blpassive.htm http://www.englisch-hilfen.de/en/exercises_list/passiv.htm http://www.autoenglish.org/gr.pas.i.htm http://a4esl.org/q/h/vm/active-passive.html
 * Passive voice**

Again in the first and second links you will find information and exercises. The others are exercises http://www.ego4u.com/en/cram-up/grammar/relative-clauses http://esl.about.com/library/grammar/blgr_relative_intro.htm http://www.englisch-hilfen.de/en/exercises/pronouns/relative_pronouns.htm http://www.vivquarry.com/wkshts/relative1q.html
 * Relative Clauses**