Passive Voice

Passive voice is used when the focus is on the action. It is not important or not known, however, who or what is performing the action.

Example: My bike was stolen.

In the example above, the focus is on the fact that my bike was stolen. I do not know, however, who did it.

(In the active voice, the sentence would be, “Someone stole my bike”.)

SUBJECT + FORM OF BE + PAST PARTICIPLE

My bike was stolen

Tense	Active
Simple Present	Once a week, Tom cleans the house.
Present Continuous	Right now, Sarah is writing the letter.
Simple Past	Sam repaired the car.
Past Continuous	The salesman was helping the customer when the thief came into the store.
Present Perfect	Many tourists have visited that castle.
Present Perfect Continuous	Recently, John has been doing the work.
Past Perfect	George had repaired many cars before he received his mechanic's license.
Past Perfect Continuous	Chef Jones had been preparing the restaurant's fantastic dinners for two years before he moved to Paris.

Passive

Once a week, the house is cleaned by Tom.

Right now, the letter is being written by Sarah.

The car was repaired by Sam.

The customer was being helped by the salesman when the thief came into the store.

That castle has been visited by many tourists.

Recently, the work has been being done by John.

Many cars had been repaired by George before he received his mechanic's license.

The restaurant's fantastic dinners had been being prepared by Chef Jones for two years before he moved to Paris.

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

•http://www.ego4u.com/en/cram-up/grammar/passive/exercises?past-perfect

•http://www.learnenglish-online.com/grammar/tests/passive.html