17. We let you know when Nick (to phone). 18. Ву seven о'clock he (to drive) for nine hours. 19. You (to have) a house-warming when you move in? 20. Our friends (to dance) for an Sour when we come to disco.

17. We will let you know when Nick phones.

18. By seven o'clock he will have been driving for nine hours.

19. Do you have a house-warming when you move in?

20. Our friends will have been dancing for an hour when we come to disco.