Carol didn't answer the phone because she was studying.

- If Carol had not been studying, she would have answered the phone.

1. Rita is exhausted today because she didn't get any sleep last night. 

- If Rita had got some sleep last night, she wouldn't be exhausted today.

2. She's very thin; perhaps that's why she feels cold so much.

- If she weren't too thin, she would feel cold so much.

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

- If he polised his shoes, he would look smart.

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

- If he could park near his office, he would come by car.

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

- If my house weren't guarded by two  big dogs, it would be broken into everynight.

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

- If the flats were clearly numbered, it wouldn't be difficult to find anyone.

7. I don't know her e-mail address, so I can't tell you

- If I knew her e-mail address, I could teel you.

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

- If she didn't work in the evening, she would have time to play with her children.

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

- They would be upset, if I told them what happend.

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

-If I were tall, I could join the basketball team.

11. He doesn't see the signal so he doesn't stop his car

- If he saw the signal, he would stop his car.

12 Peter gets bad marks because he doesn't prepare his lessons well

- If Peter prepared his lesson well, he would get good marks.

13 Mary doesn't have enough money. She can't buy a new car

- If Mary had enough money, she could buy a new car.

14. Go right now or you'll be late for the train.

- If you don't go right, you'll be late for the train.

15. He doesn't apply for the job because he doesn't have enough qualifications.

- If he had enough qualifications, he could apply for the job.

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

- If we don't hurry up, we'll be late for the exam.

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

- If you talked to them, they would understand you.

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

- If you spoke English naturally, they would understand you.

20. Keep silent or you will wake the baby up.

- If you don't keep silent, you'll wake the baby up.

22. She will help you. You tell her.

- If you told her, she would help you.

24. I was stuck in the traffic jam, that's why I came late.

- If I had come earlier, I wouldn't be stuck in the traffic jam.

25. 1 don't have his phone number, so I can't phone him.

- If I had his phone number, I could phone him.

0,  If Carol hadn't been studying, she would have answered the phone

1, If Rita had gotton any sleep last night, she wouldn't have been exhausted today

2, If she hadn't been very thin, she wouldn't have felt cold so much

3,  If he had polished his shoes, he would have looked smart

4,  If he could park near his office, he would come by car

5,  If my house weren't guarded by 2 big dogs, it would break into every night

6,  If the flats were clearly numbered, it wouldn't be very difficult to find anyone

7, If i knew her e mail address, i could tell you

8, If she didn't work in the everning, she could play with her childrent

9,  they were upset if i would tell them what happened

10,  If i were tall enough, i could join the basketball

11,  if he saw the signal, he would stop his car

12, If Peter prepared his lessons well, he wouldn't get bad marks

13,  If mary had enough money, she could buy a new car

14, If you don't do right now, you'll be late for the train

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

16.  If we don't hurry up, we'll be late for the exam

17,  If you often take to them, theu'll understand you

18. If you spoke E unnaturally, they would understand you

20, If you don't keep silent, you will wake the baby up

22,  If you tell her, she will help you

24, If i had't been stuck in the traffic jam, i wouldn't have come late

25, If i had his phone number, i could phone him