=>
A/
1. Unless you study harder, you'll fail the next exam.
2. Unless he practices writing every day, he can't improve his writing skill.
3. If this man isn't a driver, he can't help you move by car.
4. If you don't go out more often, yu might fall ill.
5. If he diddn't cleaned up the car now, his boss could ask him to do this.
6. If they weren't absent now, they would meet the headmaster.
7. Unless I knew the number, I would not ring her up.
8. Unless my sister had a terrible headache, she wouldn't be absent from her class.
9. If I had enough money, I would buy it.
10. If she didn't eat many chips, John wouldn't be fat.
11. If we had a garden, we would grow our own vegetables.

B/
1. Lan said that she would be very busy the following day.
2. His sister said that she didn't buy that book.
3. They said that they had done it the day before.
4. He said that his wife would make lemon juice.
5. Her mother said that she had to do her homework every day.
6. Charles said that he was living in London then.
7. Judy said that John wanted to come there but he wasn't very well.
8. Tom told John to turn off the T.V.
9. The robber asked the bank clerkto open the safe.
10. I asked Peter not to touch that switch.
11. Susan told her children not to run around the edge of the swimming pool.

C/
1. will feel
2. have
3. were
4. will pass
5. would stop
6. got up
7. would you cook
8. knew
9. have been
10. has worked
11. have studied
12. has eaten
13. have known
14. have travelled
15. have played