1. These houses were built by them in 1902.
2. A cake is baked by her every Sunday.
3. The vase was broken by him yesterday.
4. The shoes are cleaned by me every Friday.
5. The exercise was written by us an hour ago.
6. This road is used by them very often.
7. His car was stolen by thieves.
8. All the flights were cancelled by them.
9. The truth was told by Brian.
10. The dishwasher is always loaded by her.
11. The shopping is sometimes done by him.
12. Peter was taken to hospital by the ambulance.
Note: Expressions of time can also be put at the beginning of the sentence!