【题目】________he can't understand is ________his son doesn't like the school.He is very upset about this.
A. That；why B. Why；that
C. What；why D. Whether；that
在线课程【答案】C
【解析】句意：他不明白的是他儿子为什么不喜欢这所学校，他对此非常不安。
本句中有两个从句，前一个是主语从句， understand缺宾语，选what，后一个是表语从句，表语从句缺原因状语，选why。故选C。