Form : ( Modal + be + past participle (verb 3) )

In English we use the passive voice when :

• we are more interested in the activity being done than the person or thing that performs the action.
  
• we don't know who or what does the action.
  
• it is obvious who does the action
• we write news reports and articles.
  

In passive sentences we can use 'by' to say who or what did the action. This is called the agent. 

The passive voice is used when focusing on the person or thing affected by an action. Only verbs that take an object can be used in the passive voice.

The main verb is always in its past participle form.

Example sentences :

• All tickets must be collected 30 minutes before the show.
• Children should be seen but not heard.
• Cars must not be parked across driveways.
• Should the new metro be completed by May?
• Can your car be fixed?
  
  

Other passive structures :

After verbs followed by a gerund we use being + past participle.

eg. Some people enjoy being told what to do.

After verbs followed by the infinitive with to we use to be + past participle.

eg. Children need to be brought up in a loving environment.

After prepositions we use being + past participle.

eg. She dreams of being chosen to represent England in the Olympics.

After the first/ second/ last (+noun) we use to be + past participle.

eg. The first events to be announced were the acrobats and the clown show.

After have to and used to we use be + past participle.

eg. The graduation party had to be called off due to bad weather.

Note for use of passives :

In English we don't use the present perfect continuous and past perfect continuous in the passive!