17. unless you leave your house unlocked, it will be broken into.

18. unless you take part in the E club , your speaking skill will be improved.

    if you don't take part in the E club, your speaking skill will be improved.

19. unless you keep your feet dry, you will have a cold.

      if you don't kêp your feet dry,you will have a cold.

20. unless you want to go out tonight, make your room.

21. unless he makes more mistakes, i'll be very angry.

22. unless she forgets the book , she can share with me.

23. unless you turn down the radio, you will make the baby up.

      if you don't turn down the radio,you will make the baby up.

24. unless someone breaks into your house, you will phone the police first?

25. unless he asks to bring hot water, tell him to wait for 5 minutes.