Passive voice is used when the focus is on the action rather than the subject performing the action. In passive sentences, the thing receiving the action becomes the subject. The thing doing the action can be optionally included at the end of the sentence. Passive voice is useful when the actor is unknown, unimportant, or when using passive voice makes a statement more polite by omitting blame. Passive voice follows a formula of [subject] + [be] + [past participle] + [optional by phrase]. Active voice sentences can be changed to passive voice by making the object of the active sentence the subject of the passive sentence.

1. Passive voice.

2. Use of Passive:
Passive voice is used when the focus is on the action. It is not
important or not known, however, who or what is performing the
action.
Example: My car was stolen.
In the example above, the focus is on the fact that my bike was
stolen. We don't know, however, who did it.
Sometimes a statement in passive is more polite than active voice,
as the following example shows:
Example: A mistake was made.
In this case, I focus on the fact that a mistake was made, but I do
not blame anyone.

3. Estructure Form:
In passive sentences, the thing receiving the action is the subject
of the sentence and the thing doing the action is optionally
included near the end of the seåntence. We can use the passive
form if you think that the thing receiving the action is more
important or should be emphasized. We can also use the passive
form if you do not know who is doing the action or if you do not
want to mention who is doing the action.
[Thing receiving action] + [be] + [past participle of verb] +
[by] + [thing doing action]
Forms of uses:
Present simple: Once a week, the house is cleaned by peter.
Simple past: The car was repaired by Sam.
Present perfect: That castle has been visited by many tourists.
Past perfect: Many cars had been repaired by Peter before he
received his mechanic's license.
Future simple: The task will be finished by 5:00 PM.
Future with going to: A beautiful dinner is going to be made by
Peter tonight.
With modal verb: Pancakes can be made on a stove.
How to make active to passive:

4. Example sentence
·The dog bit the man.
Step 1:
•Find the object of the verb. (the man)
•Make the object the subject of the new sentence.
The man...
Step 2:
•Decide which tense the verb is in. "Simple past" (see chart)
•Put the verb "to be" of this tense.
•(look to see if the subject is singular or plural)
The man was...
Step 3
•Write the participle of the verb after the verb "to be"
•The man was bitten .............
The man was bitten..
Step 4
•Decide if you want to include the agent in the sentence.
The man was bitten by the dog.
Transformation examples:

5. 1 I will clean the house every Saturday. (active)
The house will be cleaned by me every Saturday. (passive)
2 The staff is required to watch a safety video every year. (active)
A safety video will be watched by the staff every year. (passive)
3 She faxed her application for a new job. (active)
The application for a new job was faxed by her. (passive)
4 Tom painted the entire house. (active)
The entire house was planted by Tom. (passive)
5 The teacher always answers the students’ questions. (active)
The students’ questions are always answered by the teacher.
(passive)

6. 1 I will clean the house every Saturday. (active)
The house will be cleaned by me every Saturday. (passive)
2 The staff is required to watch a safety video every year. (active)
A safety video will be watched by the staff every year. (passive)
3 She faxed her application for a new job. (active)
The application for a new job was faxed by her. (passive)
4 Tom painted the entire house. (active)
The entire house was planted by Tom. (passive)
5 The teacher always answers the students’ questions. (active)
The students’ questions are always answered by the teacher.
(passive)