I can't figure out it is that makes him so difficult at school.A. how B. whatC. whyD. whi

问题补充：

I can figure out it 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：B 考察强调句型和宾语从句的语序。What it be that强调句式中的强调的是主语，首先要排除how,why，又因为预计中的主语是泛指意义，排除which，有范围。故使用what。