puzzled the mother most was the son would never agree with her.A. What; whyB. That; howC

问题补充：

puzzled the mother most was the son would never agree with her.

A. What; why

B. That; how

C. Which; when

D. What; where

答案：

A. What; why

B. That; how

C. Which; when

D. What; where

解析：这里考复合句，前一空引导主语从句，第二空引导表语从句。