Ex3:
1. If the water weren't too dirty, we could bathe in this part of river.
12. If we didn't have four air conditioners in our house, we wouldn't spend too much money on electricity.
13. If I had Linh's address, I could write to her.
14. If Dick didn't drive carelessly, he wouldn't often cause accidents.
15. If we didn't waste a lot of money on unnecessary things, we could give much help to the poor.
Ex4:
16. Tom wasn't allowed to take these books home.
17. Exercises won't be corrected by the teacher tomorrow.
18. Many people are attracted by this well-known library.
19. The meeting was attended by all students.
20. My bike can't be repaired.
