The passive pattern and its purpose

The basic passive pattern is:

[thing receiving the action] + [be] + [past participle] + [by + doer]

The form of be changes with the tense. The past participle stays after it: cleaned, written, repaired, or the third form of an irregular verb such as built.

Active: Peter cleaned my car.
Passive: My car was cleaned by Peter.

The object of the active sentence becomes the subject of the passive sentence. The original subject becomes the agent after by. The agent is optional:

My car was cleaned yesterday.

This sentence is complete even though it does not say who cleaned it.

Use the passive when the receiver is more important or should be emphasised, when the doer is unknown, or when you do not want to mention the doer. In a passive sentence, the subject undergoes the action of the verb.

Important. Do not put every verb into the passive. A passive form normally needs a verb that has an object in the active sentence.