【题目】The reason he is late isthere was a breakdown on the railway．
A.why; that
B.because; that
C.that; because
D.why; why

【答案】A
【解析】经过分析句子结构，可知这个句子中包含一个定语从句和一个表语从句。关系词在定语从句中作原因状语，故用why。引导词在表语从句中不作任何成分，且没有实际意义，故用that。