The reason   （）     he was late for school was  （）       he had to send his mother to a hospital.

题目解析 答案：C 解析：这是一道考查原因和结果关系以及宾语从句的题目。正确答案是C，即 "why; that"。正确的句子应该是 "The reason why he was late for school was that he had to send his mother to a hospital." 这里第一个空是表示原因的宾语从句，使用 "why" 引导；第二个空是表示结果的宾语从句，使用 "that" 引导。