1) He can’t go out because he has to study for his exam.
=> If he hadn’t didn't have to study for his exam, he could go out. 
2) She is lazy so she can’t pass the exam.
=>If she studyied hard, she could pass the exam.
3) He will pay me tonight; I will have enough money to buy a car.
=> If he will pay me tonight, I will have enough money to buy a car.

4) She is very shy, so she doesn’t enjoy the party.
=> If she weren’t very shy, she would enjoy the party.
5) You must tell me the whole truth or I won’t help you.

=> Unless you tell me the whole truth, I won't help you
6) He doesn’t take any exercises. He is so unhealthy
=>If he took some exercises, he weren't so unhealthy

7) Study hard or you won’t pass the exam.
=> If you study hard, you will pass the exam.
8) Don’t be impatient or you will make mistakes.
If you are impatient, you will make mistakes.

1. if he đint't have to study for his exam , he could go out

2. if she weren't lazy she could pass the exam 

3. if he didn't pay me tonight , l wouldn't have enough money to buy a car

4. if she weren't very , she would enjoy the party

6. if he weren't so unhealthy  , he would take some exercises