В пособии рассматриваются основные моменты английской грамматики: части речи имя существительное, имя прилагательное и наречие; видо-временные формы глагола; модальные глаголы; неличные формы глагола

C. Passive structures are also used when we want to talk about an action, but
we are not interested in saying who (or what) did it.
Those pyramids were built around A.D.400.


D. Passives are very common in scientific writing, and other kinds of
expression where we are most interested in events and processes: in things
that happen. We see it especially in textbooks and reports. We use it to
describe activities in industries, science and technology, and also for official
rules:
Bananas are exported to the USA.
The liquid is heated to boiling point.
Payment can be made at any post office.
These gates will be locked at 9.00 pm.
The passive is often used in news reports:
A number of political prisoners have been released.
Negotiations will be held in London next week.

7. The Passive is Used:

A. When it is not necessary to mention the doer of the action as it is obvious
who he is/was/will be:
The streets are swept every day. You will be X-rayed.


B. When we don’t know, or don’t know exactly, or have forgotten who did the
action:
The minister was murdered. I’ve been told that...


C. When there is an ‘empty’ subject of an active verb such as you, one, they,
people or someone:
Active Passive
You/One should check the details. The details should be checked.
They’re increasing the rents. The rents are being increased.
People use this footpath every day. This footpath is used every day.
Someone took my purse. My purse was taken.
The passive form is more usual here, though in colloquial speech we can use
the ‘empty’ subject and the active verb.


D. When we are more interested in the action than the person who does it:
The house next door has been bought (by a Mr Jones).
If, however, we know Mr Jones, we would use the active:
Your father’s friend, Mr Jones, has bought the house next door.
E. The passive may be used to avoid an awkward or ungrammatical sentence.
This is usually done by avoiding a change of subject. So the sentence When
he arrived home a detective arrested him would be better expressed When
he arrived home he was arrested (by a detective).


F. The passive is sometimes preferred for psychological reasons. The speaker
may know who performed the action but wish to avoid giving the name.
Tom, who suspects Bill of opening his letters, may say tactfully:
This letter has been opened! instead of You’ve opened this letter!