Function of Passive Voice
When you learn how to use a certain grammatical form it should first be clear what this form can be used for.
In the case of the passive voice we can notice that the agent can totally disappear from the sentence and
the patient takes the front position. This has two effects:
First the patient becomes the topic of the sentence and
second because the agent is not mentioned, the action itself becomes the focus
of the information.
In our daily world we can mainly find two reasons why the agent is not mentioned in a sentence: It is
either unknown or unimportant.
The first case is totally clear.
When you leave your house in the morning and can't find your car you will probably call the police and say
"My car has been stolen."
Of course you could also say:
"Somebody has stolen my car",
but that would not provide any new information because that somebody is very unspecific.
The real agent is unknown and that's why it will often be left out of the sentence.
The second case is also not very complicated.
You take your car to the garage and tell your colleagues during your breakfast talk:
"My car is being repaired".
You get a general murmur of acknowledgement. Of course you could also say:
"Mr Smith, the nice mechanic in that neat blue overall, is repairing my car".
However, your colleagues will frown at you because they are simply bored by such detailed information and they
will also start wondering what sort of special relationship you have to that mechanic in the neat blue overall.
(Too much information can be harmful!) Moreover, it will usually be unimportant which of the mechanics repairs
your car at the garage and thus it won't be mentioned at all.
Other very obvious examples...
...of situations in which the agent is unknown are general descriptions or technical manuals>.
There you normally don't describe who performs an action but what actions must be performed.
So now that you know why to use the passive voice you only have to learn how to do that.
(This sentence is meant to motivate you.)
Go back to the passive voice main page.