17. Study hard or you won’t pass the exam.

->If ...................................................................................

18. I don’t have money . I can’t buy that house.

->If ...................................................................................

19. If he does n’t study hard ,he will fail the exam.->Unless……………………………………………

20. If  he doesn’t cut his hair ,they won’t let him in.->Unless……………………………………………

21.Stop telling lies or no one will trust you anymore.

 If.....................................................................

22.Pay attention to the teacher or you can’t understand the lessons.

 If.....................................................................

23.Go to bed early or you may be exhausted the next morning.

 If.....................................................................

24.Save money from now and you can reward yourself with a long vacation at the end of the year.

 If.....................................................................

25.Read more books and you can broaden your knowledge.

 If.....................................................................

26.Brush your teeth often in order not to get toothache.

 If.....................................................................

27.Listen carefully or you won’t know what to do.

If.....................................................................

28.Unless you want to get sick, you should eat more healthily.=> If.....................................................................