(单选题)

______ he won the first prize in the competition greatly enhanced his confidence.

A.What

B.When

C.Which

D.That

参考答案：D

参考解析：

考查that引导的主语从句。句意：他在比赛中获得一等奖大大增强了他的信心。分析句子成分可知，______ he won the first prize in the competition为主语从句，谓语动词为enhanced，his confidence充当其宾语。结合语境可知，主语从句的成分和语义均完整，应填入连接词that。故选D。

知识点：