1. I was given a bonus.
2. The work will be finished by Monday.
3. The bread is baked every morning.
4. The letters are written right now.
5. I couldn’t drive yesterday, my car was in service либо was repaired. Was serviced нельзя. Если учитель будет настаивать на этом варианте, забейте, учитель не знает язык
6. thieves were taken into custody by the police
7. when I arrived at the office the letter had already been sent правильно, но если уж учитель настаивает, что тут с какого-то перепугу пассив, то when I arrived at the office the letter was already sent
8. tea is grown in India
9. my money were stolen from my room yesterday
10. the bench was painted a moment ago (вообще то это present perfect типа recent action: the bench has just been colored)
11. flowers are watered in the evening
12. the book is not sold everywhere
13. chocolate is made from cocoa
14. I was born in Tuapse
15. I will be sent to take part in a competition