Actions can be described using either the active or the passive voice, depending on whether we are interested in what the subject does, or what happens to it.
Actions can be described using either the active or the passive voice. In the active voice, the subject and what it does is of most interest. In the passive, the person or thing receiving the action becomes the grammatical subject and the focus of the sentence.
active voice: My father built this house.
passive voice: This house was built by my father.
We create the passive form by conjugating the verb "to be" and adding it to the past participle of the main verb. The tense of the verb "to be" determines the tense. When the agent of the action (that is, the person or thing performing the action) is described, we introduce it with the preposition "by":
The Mustang is made by Ford in America.
Manchester United were recently beaten by Chelsea.
The passive form is used for a variety of reasons:
When the object of the main verb is more important (to the speaker) than the subject.
When the person or thing that performed the action (the subject) is unknown.
When the person or thing that performed the action (the subject) is obvious.
When we prefer not to identify the person or thing that performed the action (the subject).
When explaining (for example) a manufacturing process where the agent is irrelevant.
My house was built by Barrett Homes. (I'm talking about my house, not about Barrett Homes.)
My car is being repaired. (I think the mechanic is called Steve, but it is not important.)
Her car was stolen last night. (I don't know who stole it)
My computer has been switched off! (I don't know who did it.)
She was arrested for drink-driving last night. ('By the police' is not necessary. It is obvious.)
They were taken to hospital after the accident. ('By an ambulance' is not necessary. It is obvious.)
Mum, the window has been broken. (I don't want to mention that I broke the window..)
I'm afraid it has been decided to end your contract. (I made the decision, but I prefer not to say this.)
First, the raw material is taken to the warehouse, where it is checked. Next, it is taken to the factory for processing.
The passive is frequently used in English, but it should not be used too often. As an alternative, it is possible to use an impersonal subject, such as "one" or "someone"
(passive voice): This job needs to be done.
(active voice): Someone needs to do this job.