1. Introducing the Passive
Look at the following sentences.
Sentence A: People eat sushi in many parts of the world.
Sentence B: Sushi is eaten by people in many parts of the world.
Sentence A is considered active because the doer of the action (or agent) is the subject of the sentence.
Sentence B is passive. That is, the object of the active verb (eat) in the first sentence is the subject of the passive verb (is eaten) in the second sentence. This means that only verbs which have objects (transitive verbs) can be made passive.
Active sentences are usually regarded as stronger than passive sentences. Passive sentences are common, however, especially in academic writing. In fact, there are three situations when it is better to use a passive sentence instead of an active one. They are listed below.
Using the Passive
Situation One: When we don't care or don't know who performs the action.
The injured workers were rushed to the hospital.
Situation Two: When we can't or don't want to say who performed the action.
Has the truth been hidden from us?
Situation Three: When we want to place emphasis on the receiver of the action rather than the doer, or agent.
Thousands of homes were destroyed by the hurricane.
2. Forming the Passive
We form the passive by using the correct form of the verbs “be” (is, am, are,be, been, being, was, were) or “get” (get, gets, getting, got, gotten) plus a past participle. Be careful. Passive sentences with get plus a past participle are less formal than those with be plus a past participle. Consequently, they are most often used in spoken English and informal writing.
Most of the trash got taken to the recycling centre. (informal)
Most of the trash was taken to the recycling centre. (formal)
Using the “by phrase”
As you have learned, passive sentences are used when writers don't know or don't care who actually performed the action. Thus, the majority of passive sentences do not include “by phrases”. Only when it is important for readers to know who performs the actions, do writers include it in passive sentences. Consider the following examples.
That building was designed by a famous architect.
(The “by phrase” is important, so it is included.)
“Macbeth” and “King Lear” were written by William Shakespeare.
(The “by phrase” is included because it is important.)
The mail is usually delivered before noon.
(The “by phrase” is not necessary because we know who delivers the mail each day.)