I can’t understand is he wants to change his mind.
A. that; that
B. what; why
C. which; what
D. what; 不填
网友回答
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。