Active = "The doctor gave me a prescription"
Passive = "I was given a prescription"In the first sentence, the focus is on 'the doctor'. In the second sentence, the focus is on 'I'.
When to use the passive
To change the focus of a sentence.
In the passive sentence above, we can make the object and action ('me' and 'gave a prescription') more important than the subject ('the doctor').
If we don't know who does an action.
"My bicycle has been stolen" – I don't know who has stolen it.
If we don't want to say who did something.
"The lights were left on all night." (I don't want to say that you left the lights on.)
If it is obvious who does something.
"I was given a prescription" – I know that only doctors give prescriptions, so I don't need to add "by the doctor".
"He was arrested" I know that the police arrest people, so I don't need to add "by the police".
Forming a passive sentence in English
Firstly, you need to make the object into the new subject.
me – I
you – You
him / her – He / She
us – We
them – They
Then you make the verb passive.
Put the verb "to be" into the same tense as the verb in the active subject. For example "gave" is the past simple tense. The past simple form of "to be" is "was" or "were".
Present simple – is /are
Present continuous – is / are being
Present perfect – has / have been
Simple past – was / were
Past continuous – was / were being
Modals will, can etc – will be, can be etc.
Then add the past participle of the verb. For example "gave" – "given".
How to use Passives in English, Passives in English