We should spend ______ money solving ______ problems.

Why are there so many people in the restaurant-It starts business today and the drinks____ for free.

When ____ to compare the education system of China and Britain, the professor gave no answer．

Your neighbours may ____ you of playing the piano at midnight. —I know. They never say anything favorable to me.

It is playing computer games _______ theboy spends most of his spare time