My neighbors used to give a hand in time of trouble was very kind of them.A. whoB. thatC.

问题补充：

My neighbors used to give a hand in time of trouble,was very kind of them.

A. who

B. that

C. what

D. which

答案：

A. who

B. that

C. what

(答案→)D. which

解析：考查定语从句。Which指代前面主句并在从句中作主语。