2. The passive In an ACTIVE sentence, the subject is the person or thing that performs the action: Masked thieves stole a valuable painting from the museum last night. When you take this into PASSIVE sentence, the object of the verb becomes the subject: A valuable painting was stolen from the museum last night.
3. The passive contd… The passive is formed with the auxiliary verb be and the past participle of the verb: The painting is valued at 2 million dollars. The lock had been broken and the cameras had been switched off.
4. Use the passive When you do not know who performed the action, or when this information is not important. It is common in formal writing, for example scientific writing: The liquid is heated to 60o and then filtered. Note: If you want to mention who performed the action, you use by at the end of the sentence: The theft is being investigated by the police.
5. Use of passive contd… When you want to serve new or important information until the end of the sentence for emphasis: The picture was painted by Constable. It is possible to put a verb that has two objects into the passive: (active) The director told the staff the news this morning. (passive) The staff were told the news this morning by the director. Some verbs cannot be used in the passive, and this is shown at the entries.