Page 417 - Practical English Usage 3ed - Michael Swan, Oxford

passives (1): passive structures and verb forms 412
412 passives (1): passive structures and verb forms 1 active and passive structures
Compare:
- They built this house in 1486. (active)
This house was built in 1486. (passive) - Austrians speak German. (active)
German is spoken in Austria. (passive)
- A friend o f ours is repairing the roof. (active)
The roof is being repaired by a friend of ours. (passive) - This book will change your life. (active)
Your life will be changed by this book. (passive)
When A does something to H, there are often two ways to talk about it. If we want A (the doer) to be the subject, we use an active verb: built, speak, is repairing. If we want H (the 'receiver' of the action) to be the subject, we use: was built, is spoken, is being repaired, will be changed.
The object of an active verb corresponds to the subject of a passive verb.
OBJECT
Active: They built this house in 1486.
Passive: This house was built in 1486. SUBJECT
In most cases, the subject of an active verb is not expressed in the corresponding passive sentence. If it does have to be expressed, this usually happens in an expression with by; the noun is called the 'agent' (see 413).
This house was built in 1486 by Sir John Latton. 2 passive verb forms
We normally make passive forms of a verb by using tenses of the auxiliary be followed by the past participle (= pp) of the verb. (For get as a passive auxiliary, see 223.5.) Here is a list of all the passive forms of an ordinary English verb.
Name
(simple) future future perfect
simple present present progressive
present perfect simple past past progressive past perfect
Construction will be +pp
will have been +pp am/are/is + pp
am/are/is being + pp have/has been +pp
was/were + pp was/were being + pp had been + pp
Example
You'll be told soon enough. Everything will have been
done by Tuesday English is spoken here. Excuse the mess; the house
is being painted.
Has Mary been told?
I wasn't invited, but I went.
I felt as ifI was being watched. I knew why I had been chosen.
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