Mình trình bày trong hình.

@ `Ly`

=>
1. If I had enough money, I would buy it.
2. I would have bought it if I had had enough money.
3. If I had known that there was a test yesterday, I would have studied for it.
4. I could help you if I weren't busy right now.
5. If he weren't very thin, he wouldn't feel the cold so much.
6. If I had eaten breakfast several hours ago, I wouldn't be hungry now.
7.  Unless John had played for our football team, we would have lost the game.

8. Unless I won a big prize in a lottery, I wouldn't give up my job.
9. Unless you like this one, I'll bring you another.
10. Unless you promise to try harder, I won't help you.
11. She'll lose her job unless she works harder.
12. If you keep my car carefully, you can use my car.
13. If I had finished the work by lunch, I could have gone home.
14. If you keep calm, you will pass your driving test.
15. You won't pass the exam if you don't work harder.
16. I'll never speak to her again if she doesn't apologize to me.

18. Unless you leave me alone, I'll call the police.
19. If the weather weren't snowy, we would go to school.
20. If Jack hadn't help me, I wouldn't have been able to move the table.