Mr. Smiths was busy writing a story, only ______ once in a while to smoke a cigarette.

I walked out of the cinema, ______ to return to see the wonderful film next Sunday. 

___ from space, the earth with water ___70％ of its surface looks like a "blue blanket". 

Nowadays teachers feel they can’t help every student ________ suitable reading materials, so they encourage them __________ English on the Internet.

He used to ______ cards, but now he is used to _______ a walk after supper.