题目内容：

Do you konw the reason ___he came late for school?Yes,The reason is __he was stuck in a traffic.
A,that,because B,why,that C,why,because D,that,why

优质解答

B 前面一个空是 the reason why 即某事的原因 后面一个空是表语从句 that引导一个句子 即reason的具体内容