1. She doesn’t live in London because she doesn’t know anyone there.

⇔   She'd live in London if she knew someone there.

2. I can't live in the country because I can't find a job there.

⇔   I'd live in the country if I could find a job there.

3. I don't have a spare ticket. I can't take you to the concert.

⇔   If I don't have a spare ticket, I will can't take you to the concert.

4. The school children sowed some seeds, but they forgot to water them so they didn't grow.

⇔   If the children hadn't forgotten to water the seeds, the would have grow.

5. They don't understand the problem. They won't find a solution.

⇔   If they don't understand the problem, they won't find a solution.

6. He sits around too much. He isn't fit.

⇔   If he did sit around too much, he would isn't fit.

7. Carol didn’t answer the phone because she was studying.

⇔   If Caron had been studying, she would haven't answered the phone.

8. Rita is exhausted today because she didn’t get any sleep last night.

⇔   If Rita didn't get any sleep last night, she would exhausted today.

9. She’s very thin; perhaps that’s why she feels cold so much.

⇔   If she is very thin, she will feel cold so much.

10. He never polishes his shoes, so he never looks smart.

⇔   If he doesn't looks smart, he won't polish his shoes.

11. He can’t park near his office; that’s why he doesn’t come by car.

⇔   If he didn't park near his office, he wouldn't come by car.

12. My house is guarded by two big dogs. That’s the only reason it isn’t broken into every night.

⇔   If my house were guarded by two big dogs, it won't broken into every night.

13. The flats are not clearly numbered, so it is very difficult to find anyone.

⇔   If the flats wasn't clearly numbered, it would very difficult to find anyone.

14. I don’t know her e-mail address, so I can’t tell you.

⇔   If I don't know her e-mail address, I will can't tell you.

15. She works in the evening. She has no time to play with her children.

⇔   If she works in the evening, she won't have time to play with her children.

16. I don’t want them to be upset, so I’ve decided not to tell them what happened.

⇔   If I don’t want them to be upset, I won't tell them what happened.

17. I am not tall enough to join the basketball team.

⇔   If I am tall, I will join basketball team.

18. He doesn’t see the signal so he doesn’t stop his car.

⇔   If he doesn't see the signal, he won't stop his car.

19. Peter gets bad marks because he doesn’t prepare his lessons well.

⇔   If Peter doesn't prepare his lesson well, he willl get bad marks.

20. Mary doesn’t have enough money. She can’t buy a new car.

⇔   If Mary had enough money, she would buy a new car.

21. Go right now or you’ll be late for the train.

⇔   If you don't go right now, you will be late for the train.

22. He doesn’t apply for the job because he doesn’t have enough qualifications.

⇔   If he had enough qualifications, he would apply for the job.

23. Hurry up, or we will be late for the exam.

⇔   If we don't hurry up, we will be late for the exam.

24. They do not understand you because you do not often talk to them.

⇔   If you often talk to them, they will understand you.

25. Because you speak English unnaturally, they do not understand you.

⇔   If you speak English unnaturally, they won't understand you.

       Chúc bạn học tốt môn Tiếng Anh 8 nhaaa! :>