________ is known to everybody, Taiwan is a part of China. We must unify it.

A.It

B.As

C.Which

D.What

答案及解析： B

解析：

先行词是Taiwan is a part of China整个主句，一般由as或which引导定语从句，但which引导的定语从句只能放在主句之后，另外，as有“正如”之意，而which没有，所以用as。顺便说说，原句改为：It is known to everybody that Taiwan is…=" What" is known to everybody is that Taiwan is…