We should wear special boots __________ us floating away into the space .

He is very serious. No one can make him___.

The students should ________ to choose their own clothes. It will be a good way _____ themselves happy. 

 It is better for you to walk down the stairs instead of ________ the elevator.

---- You'd better_______ some popcorn or soft drinks before the film begins.---- But I think it's better _______ anything while watching the film.