Question

We'd better       when he is thinking, as he prefers to solve problems on his own.

A. let him down

B. cheer him up

C. leave him alone

D. ring him up

Answer

C

【解析】句意：当他正在思考的时候，我们最好让他一个人呆着，因为他喜欢自己解决问题。let him down让他失望了；cheer him up使他振作起来；leave him alone不干涉他，不打扰他；ring him up给他打电话。根据句意as he prefers to solve problems on his own可知，他喜欢自己解决问题，所以这里是不要打扰他。故选C。