Passive voice

In the passive, the object of an active verb becomes the subject of the passive verb. For example, "Marry helped the boy". The boy in this sentence becomes the subject of the passive verb. It becomes, "The boy was helped by Marry".

Notice that the subject of an active verbs follow by in a passive sentence. The noun that follows by is called the "agent". "Marry is the agent". Only transitive verbs (verb that can be followed by an object) are used in the passive. It is not possible to use intransitive verbs (such as happen, sleep, come, and seem) in the passive.

Form of the passive: be + past participle

-The boy is helped by Marry -The boy is being helped by Marry -The boy has been helped by Marry -The boy was helped by Marry -The boy was being helped by Marry -The boy had been helped by Marry -The boy will be helped by Marry -The boy is going to be helped by Marry -The boy will have been helped by Marry

In the question form of passive verbs, an auxiliary verb precedes the subject. (From English Grammar Third Edition by Betty Schrampfer Azar)