I can’t understandit is that makes him so difficult at school.A. howB. whatC. whyD. which

问题补充：

I can’t understandit is that makes him so difficult at school.

A. how

B. what

C. why

D. which

答案：

A. how

(答案→)B. what

C. why

D. which

解析：强调句型考查题。强调的部分为understand的宾语从句的主语用what。