See also PDF exercises below.
The passive voice is formed with the verb to be and the past participle, which is different for regular verbs (fixed) and irregular verbs (taken).
Statements:The car was repaired. The text was written.
Questions: Was the text written?
Negatives: The text was not written.
In the examples above the agent is not mentioned. We do not know who repaired the car or wrote the text.
If we want to say who repaired the car we mention the agent at the end of the sentence and use the preposition by.
The car was repaired by my brother.
If there are both direct and indirect objects in the active voice (My friend sent me a letter), the indirect object (my friend), not the direct object (a letter), becomes the subject in the passive voice.
Active: My friend sent me a letter.
Passive: I was sent a letter by my friend. (Not: A letter was sent to me by my friend. This sentence does not sound natural in English.)
The passive is used:
1. If the action is more important then the agent.
A demonstration was held. This theatre was built in 1868.
The important thing is what happened, not who did it.
2. If the agent is not known.
He was offered a job. (Someone offered him the job.)
They were supposed to be good students. (Some teachers supposed that.)
This form is typical of an impersonal and formal style. In a less formal style the active voice is more usual.
He was seen in Dover. - They saw him in Dover.