1. These exercises were done well.
`→` They did the exercises well.
2. This dress must be washed in cold water.
`→` She must wash this dress in cold water.
3. No mistakes have been made in his composition.
`→` He hasn't made any mistakes in his composition.
4. His painting will be exhibited for the first time by New Arts gallery.
`→` They will exhibit his painting for the first time by New Arts gallery.
5. This house was built 100 years ago.
`→` They built this house 100 years ago.
6. These artificial flowers are made of silk.
`→` They make these artificial from silk.
7. The lessons are being written by the students now.
`→` The students are writing the lessons now.
8. This job has to be done at once.
`→` We have to do this job at once.
9. These animals at the zoo are fed twice a day.
`→` They feed these animals twice a day at the zoo.
10. The operation is going to be performed by French doctors.
`→` French doctors are going to perform the operation.
11. All the arrangements have been made.
`→` They have made all the arrangements.
12. When was this radio manufactured?
`→` When did they manufacture this radio?
13. They couldn't be found anywhere.
`→` We couldn't find them anywhere.
14. Is mathematics taught in this school?
`→` Is she teach mathematics in this school?
15. Fortunately the machinery wasn't damaged by the accident.
`→` The accident didn't damage the machinery fortunately.
16. Please wait here while your luggage is being examined.
`→` Please wait here while we are examining your luggage.
17. How are candles made?
`→` How do they make candles?
18. For a long time the earth was believed to be flat.
`→` For a long time they believed that the earth was flat.
19. Were you taught how to apply this theory by your teacher?
`→` Did your teacher teach you how to apply this theory?
20. Apples are said to be good for our health.
`→` They say that apples are good for our health.
21. Don't let the dog be teased by the children.
`→` Don't let the children tease the dog.
