1. The tickets have been booked in advance.
2. This information should be found next week.
3. Children are usually looked after by Miranda.
4. Two ships are being unloaded at the moment.
5. When we were at the zoo, the animals were being fed by the zoo keeper.
6. Twenty people were invited to Marvin's birthday party.
7. Before the necessary information has been found, all documents were trawled by librarian.
8. The turkey will have been roasted by Christmas.
9. The patients are usually examined on rounds.
10. My leg was pricked by an ant yesterday.
11. Soon, a new dress will be sewn by mother.
12. Lesley has just been fired.

В предложениях, где изначальное действующее лицо находится на втором плане или незначительно, его можно убрать при переделке в passive voice (как в предложениях 2, 4, 8, 9, 12).