=>
15. The milk is brought to my door by the milkman but the letters are left in the hall by the postman.
16. Dogs must be kept on leads in the garden.
17. The lock was covered by paint.
18. The teacher's question couldn't be answered correctly.
19. Jack was invited but Tom wasn't invited.
20. Has the report on rubber trees been finished yet?
II/
1. was built
2. started
3. were sent
4. went
5. was
6. was carrying
7. sank
8. was attacked
9. died
10. was seen
11. was made
12. were brought
13. was lifted
14. saw
15. was taken
16. had sunk