- We need a new leader for our Helping Hands Club but I don’t know . Why not Mary?

问题补充：

--- We need a new leader for our Helping Hands Club, but I don’t know . --- Why not Mary? She is always willing to help others.

A. what to choose

B. how to choose

C. when to choose

D. who to choose

答案：

A. what to choose

B. how to choose

C. when to choose

(答案→)D. who to choose

解析：what什么；how怎样；when什么时候；who谁。根据下文，为什么不是玛丽？她总是乐于助人的。可知上文提问的是人，故选D。