They preferred to school a bus.A. to walk, takeB. walking, to takingC. to walk, take D.

They preferred to school a bus.
A. to walk, take
B. walking, to taking
C. to walk, take
D. walk, to take

A. to walk, take(答案→)B. walking, to takingC. to walk, take D. walk, to take解析：prefer A to B表示与B相比更喜欢A，主语A和B结构一定要相同，动名词表示抽象动作，结合语境，可知选B。

就是这个解释