Теория:

Types of sentences in the passive voice.
 
1. We form positive sentences by putting the verb form on the second place:
 
SUBJECT + TO BE + PAST PARTICIPLE
 
The furniture has been delivered.
  
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2. We form questions by putting the verb to be before the subject.

Is your car being serviced?
  
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3. We form negative sentences by putting not after to have or to be.

The office has not been cleaned yet.
  
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4. You should form the passive of infinitives like this:

VERB + TO BE + PAST PARTICIPLE

He wants to be made the right decision.
  
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5. You should form the passive of modal verbs like this:

MODAL VERB + BE + PAST PARTICIPLE
 
The roof must be repaired as soon as possible.
  
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