What do you think of the reason he mentioned at the meeting winning this competition?A.

问题补充：

What do you think of the reason he mentioned at the meeting winning this competition?

A. why; why

B. that; of

C. which; why

D. \; for

答案：

A. why; why

B. that; of

C. which; why

(答案→)D. \; for

解析：通过分析句子结构，可知这个句子中包含一个定语从句，且关系词在定语从句中作宾语，先行词指物，故用that或which，也可省略。第二个空，表示“为了赢得比赛”，故用介词for。