请把以下的句子改为被动语态,急!

1.Fire destroyed much of London in the 17th century.
Much of London was destroyed by fire in the 17th century

2.We have to do something to stop population growth.
Something have to be done to stop population growth.

3.They are pulling down the old theatre.
The old theatre is being pulled down by them.

4.The manager has carefully compil(编写) the report.
The report has been carefully compiled by the manager.

5.The librarian said that they were starting a new system.
The librarian said that a new system was being started.

6.Does someone clean all the rooms regularly.
Are the rooms cleaned by someone regularly?

7.The judges will judge the applicants on the basis of their originality.
The applicants will be judged by the judges on the basis of their originality.

8.You can’t wash this dress; you must dry-clean it.
This dress cant be washed; it must be dry-cleaned.

9.The milkman brings the milk to my door but the postman leaves the
letters in the hall.
The milk is brought to my door but the letters are left in the hall.

10.You can find answers to the exercises in the Teacher’s Book.
The answers to the exercises can be found in the Teacher’s Book.

11.Two storms have hit the area in the past three weeks.
The area has been hit by two storms in the past three weeks.

12.When are we to hold the sports meet?
When is the sports meet held?

13.We assume Bill will announce his candidacy soon.
We assume bill's candidacy will be announced by him soon.