Answer:
7. Nowadays, machines are used for doing that work.
8. Nothing can be done to save him now.
9. The pineapples were cut into cubes.
10. The plant is left in the dark for a few days.
11. The accident ought to be reported to the police within twenty-four hours.
12. The expedition has been well organised.
13. A job was offered to me in his company, but I refused it.
14. A doctor had been sent for, but he had not arrived yet.
15. Every figure in the accounts book must be checked over.
Explanation:
There are a few steps we can follow to change a sentence from the active voice into the passive. Let's check them out:
1. Identify the object of the active sentence. It will become the subject of the passive.
2. Identify the subject of the active sentence. It will become the agent of the passive. However, in this activity, we were asked to leave the agent out.
3. Identify the verbs and the tense. The tense should be maintained. If there are any modal verbs (must, should, may, can, etc.), they should also be maintained. The auxiliary "be" must be added respecting the original tense. The main verb must be changed into its past participle form.
The example below will help illustrate the steps above.
-Active voice: The cat (sub.) chased (verb, simple past) the mouse (object).
- Passive voice: The mouse (sub.) was chased (simple past, aux. "be") by the cat (agent).
