The reason why he was late was   （）        he had taken a wrong bus.

题目解析 题目：The reason why he was late was （） he had taken a wrong bus. A.because B.whether C.because if D.that 答案：D 解析：这是一个原因和结果的关系题。正确的句子结构应该是 "The reason ... was that ..."，选项D "that" 在这里起到引导后面结果的作用，正确完成了句子。