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

Bell invented the telephone. The telephone was invented by Bell.

The two sentences have the same meaning, but they are about different

things. The subject of one sentence is Bell, and the subject of the other is the
telephone. The subject is the starting-point of the sentence, the person or
thing we are talking about. In both of these sentences the subject is old
information, something already mentioned.
The new information comes at the end of the sentence. We say Bell invented
the telephone because we are talking about Bell, and the new information is
that he invented the telephone.

When the subject is the person or thing doing the action (the agent), then we

use an active verb (invented). When the subject is not the agent, then the
verb is passive (was invented).
Compare:
Active (about Bell): Passive (about the telephone)
Bell invented the telephone. The telephone was invented by Bell.

Subject & agent Subject Agent

The subject of the passive sentence is the same as the object of the active
sentence (the telephone). It is not the agent. It is the thing that the action is
directed at.


B. We often prefer to put longer and ‘heavier’ expressions at the end of a
sentence, and this can be another reason for choosing a passive structure.
Compare:
Mary’s bahaviour annoyed me.
(Or: I was annoyed by Mary’s behaviour.)
I was annoyed by Mary wanting to tell everybody else what to do.
The first sentence can easily be active or passive. But if the second sentence
was active, the subject would be very long (Mary wanting to tell
everybody else what to do annoyed me). In this case, a passive structure is
more natural.