In the old days, people lived in caves and they had to make a fire _________themselves warm. 

The old radio requires____________, so you’d better have it ______soon.

-What should T do, doctor? -_______ healthy, you should take more exercise.

Tell your son ____ on the road. It’s dangerous.

 — Have you seen the film _____ Lost In Thailand  (泰囧) ？— Yes. It’s great fun . I couldn’t stop _____while I was watching it