14. You should open the window.

• The window should be opened.

15. You ought to wash the car.

• The car ought to be washed.

16. He must fill in the form.

• The form must be filled in by him.

17. You can't wash this dress.

• This dress can't be washed.

18. You should open the wine about 3 hours before you use it.

• The wine should be opened about 3 hours before it is used.