Before the problem can be solved it must be obvious the problem itself is.(·湖南 31)A.

问题补充：

Before the problem can be solved，it must be obvious the problem itself is.(·湖南，31)

A. what

B. that

C. which

D. why

答案：

(答案→)A. what

B. that

C. which

D. why

解析：句意：在解决问题之前必须弄清楚问题本身是什么。what引导主语从句，并在主语从句中充当表语。注：句中的it是形式主语。