Simple present passive and Simple past passive

 SIMPLE PRESENT PASSIVE:

Structure: AM/IS/ARE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer is repaired.

SIMPLE PAST PASSIVE

Structure: WAS/WERE + PAST PARTICIPLE (+BY+NOUM)

Ex. The computer was repaired.

More information and some exercises:

http://www.ego4u.com/en/cram-up/grammar/passive/exercises

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

 

https://elt.oup.com/student/solutions/preint/grammar/grammar_10_012e?cc=global&selLanguage=en

 

http://www.englishexercises.org/makeagame/viewgame.asp?id=1870