Решение:
1. Nobody saw him yesterday. Passive: He was not seen by anybody yesterday.
2. She will send the telegram tomorrow. Passive: The telegram will be sent by her tomorrow.
3. We are looking for the information now. Passive: The information is being looked for by us now.
4. Many tourists visit this city. Passive: This city is visited by many tourists.
5. I will have watched the film by next week. Passive: The film will have been watched by me by next week.
6. They were reading a book when he came in. Passive: A book was being read by them when he came in.
7. The pupil has put the things on the desk. Passive: The things have been put on the desk by the pupil.
8. He will be flying over the ocean tomorrow at 6 a.m. Passive: The ocean will be flown over by him tomorrow at 6 a.m.
9. The family had left the hotel by yesterday morning. Passive: The hotel had been left by the family by yesterday morning.
10. Kate invited her friends to the party last week. Passive: Her friends were invited to the party by Kate last week.