问题
选择题
The reason_________ he didn't 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
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。