The reason he didnt come was he had to take care of his sick mother.A. why ; thatB. why

问题补充：

The reason he didn come was he had to take care of his sick mother.

A. why ; that

B. why ; which

C. which ; why

D. that ; for

答案：

(答案→)A. why ; that

B. why ; which

C. which ; why

D. that ; for

解析：本题是一道定语从句与宾语从句的交叉考查。why引导的从句作为句中的定语，that引导的从句作为句中的宾语。