I can’t understand is he wants to change his mind.A. that; thatB. what; whyC. which; wha

问题补充：

I can’t understand is he wants to change his mind.

A. that; that

B. what; why

C. which; what

D. what; 不填

答案：

A. that; that

(答案→)B. what; why

C. which; what

D. what; 不填

解析：考查名词性从句。What I can’t understand是主语从句，what引导主语从句并在句中作为understand的宾语。Why he wants to change his mind是表语从句。句意：我不能理解的是为什么他不想改变想法。