1. If he didn't have to study for exam, he could go out. 

2. If she were't lazy, she could pass the exam. 

3. If he pays me tonight, i will have enough money to but a car. 

4. If he didn't smoke too much, he could get rid of his cough. 

5. If she weren't very shy, she could enjoy the party. 

6, If i get a work permit, i will stay for another month. 

7. If he took some exercises, he weren't so unhealthy. 

8. If we had the right change, we could get the ticket. 

9. If you study hard, you will pass the exam. 

10. If you are impatient, you will make mistakes. 

11. If i had eaten lunch, i wouldn't have been hungry now. 

12. Unless they invite me, i won't come. 

13. If he had revised all his lessons, he wouldn't have failed the exam. 

14. If you walk to the park, it will take you 5 minutes. 

15. Unless you leave me alone, i will call the police. 

16, Should you arrive at the office earlier than i do, please turn on the air conditioner. 

17. If it snows, the children won't go to school. 

18. Had he not died so young, he would have been a famous musician by now. 

19. Unless you tell me the whole truth, i won't help you. 

Bn học tốt!!!