Unless you promise to return back, I won't lend you

8. Unless you promise to return back, I won't lend you
If
9. we put off our trip beause the weather was terrible
If
10. Sally doesn't know what she has to do for homework beause she was absent from school on friday
If
11.If do you not like this one, I'll bring you another
Unless
12. Martin failed his driving test last week beause he was very nervous
But for
13. He will pay me toninght; I will have enough money to buy a car
If
14. Leave me alone or I'll call the police
If
15. If you arrive at the office eariler than I do, please turn on the air- conditioner
Should
16. He died so young; otherwise, he would be a famous musician by now
Had it
17. The car breaks down so often beause you don't take good care of it
Were you
18. Don't tell lies to your boss or you'll be fired at once
If
19. He didn't revise all his lessons, so he failed the exam
If