The reason he explained is she was ill.A. that thatB. which thatC. why becauseD. why

问题补充：

The reason he explained is she was ill.

A. that , that

B. which , that

C. why,because

D. why, that

答案：

(答案→)A. that , that

B. which , that

C. why,because

D. why, that

解析：考查定语从句和表语从句。第一空是定语从句，先行词为The reason，从句he explained后缺少宾语，所以用关系代词which/that，第二空是表语从句，that 无词义，起引导作用。所以选A。