The reason ________ he is late is ________ there was a breakdown on the railway．

A.why; why

B.because; that

C.that; because

D.why; that

答案及解析： D

当先行词是reason，而且在从句中作状语时，关系词要用why。一个表语从句说明reason的内容时，连接词要用that。