Interchange of Active and Passive Voice

A sentence in the Active form can be changed into the Passive form, and vice versa :-
Active. Brutus stabbed Caesar.
Passive. -- Caesar was stabbed by Brutus.
Active. -- The people will make him President.
Passive. -- He will be made President by the people.
Active. -- Who taught you grammar?
Passive. -- By whom were you taught grammar?/Who were you taught grammar by? --
By whom was grammar taught to you ?
Active. -- The Governor gave him a reward.
Passive. -- He was given a reward by the Governor.
A reward was given him by the Governor.
Active. -- The Romans expected to conquer Carthage.
Passive. -- It was expected by the Romans that they would conquer Carthage.
Active. -- One should keep one's, promises.
Passive. -- Promises should be kept.
Active. -- I know her.
Passive. -- She is known to me.
Active. -- My captors were taking me to prison.
Passive. -- I was being taken to prison by my captors.
Active. -- His behaviour vexes me sometimes.
Passive. -- I am sometimes vexed at his behaviour.
Active. -- It is time to shut up the shop.
Passive. -- It is time for the shop to be shut up.
Active. -- The audience loudly cheered the Mayor's speech.
Passive. -- The Mayor's speech was loudly cheered.
Note:- Whenever it is evident who the agent (i.e., doer of the action) is, it is unnecessary
to mention him in the passive form, and this omission gives a neater turn to the sentence.
Thus in the last example the agent is not mentioned in the passive form because only
those who heard the speech could have cheered it.