Active voice: Shakespeare
wrote both plays and poety.
Passive voice: Both plays
and poetry were written by Shakespeare.
Passive voice is constructed by using the verb "to be" as a helping verb and adding the past participle. The helping verb changes to indicate the tense.
Present tense: The sign is
read by everyone who passes.
Past tense: The sign was
read by everyone who passed.
Present perfect tense: The
sign has been read by everyone who has passed.
When is passive voice appropriate? The passive voice is appropriate for situations that emphasize the action itself rather than who performed it. The store on Main Street was robbed last night (passive voice) emphasizes what happened. Someone robbed the store on Main Street last night (active voice) emphasizes the mysterious person who committed the robbery.
When is passive voice inappropriate? When used in the wrong situation, passive voice can lead to wordy sentences that are sometimes hard to understand. Notice how the passive voice version of the sentence below lacks the directness that we expect of good writing.
Active voice: Owls hunt their
prey at night.
Passive voice: The prey
of owls is hunted at night.
The actor in a passive voice sentence may be implied or may appear in a prepositional (by) phrase, but in either case so long as you have the verb "to be" + the past participle, you have passive voice.
Intransitive verbs, those that don't have objects, have no passive form. For example, rise is intransitive. You can't rise anything, though you can raise something--cabbages, for instance. Some verbs can be used both transitively and intransitively.
Intransitive: Grass grows
in Aldrich Park.
Transitive: The gardener
grows cabbages.