Практическая грамматика

§ 17. The use of the Future Perfect Continuous.
The Future Perfect Continuous denotes an action which will begin before a definite moment in the future, will continue up to that moment and will be going on at that moment.
In ten minutes we’ll have been waiting for the bus for
exactly an hour.


The Passive Voice

The Passive Voice is formed by means of the auxiliary verb to be in the required form and Participle II of the notional verb.

§ 18. The use of the Passive Voice.
The Passive Voice can be used:
a) without the doer of the action being mentioned for some special reasons (tact or delicacy of feeling).
Enough has been said here of a subject which will be treated more fully in a subsequent chapter.
You have been told so many times not to touch these things.
b) when the doer of the action is unknown or unimportant
A lot of money was stolen in the robbery.
Is this room cleaned every day?
c) with the doer of the action being mentioned. This occurs only when the doer of the action is to some extent emphasized. The noun or pronoun denoting the doer of the action is introduced by the preposition by.
This house was built by my grandfather.
Two hundred people are employed by the company.
§ 19. The use of tenses in the Passive Voice.
The uses of tenses in the Active and in the Passive Voice are the same.
Indefinite
Present The letter is written.
Past The letter was written.
Future The letter will be written.


Continuous
Present The letter is being written.
Past The letter was being written.
To express an action going on at a definite moment in the future only the Future Continuous Active is possible. Thus the Russian sentence «Когда вы придете, опыт уже будет производиться» must be translated in the following way:
When you come, we shall already be making the experiment.