is known to all Taiwan is a part of China.A. AsB. WhichC. ThatD. What

问题补充：

is known to all, Taiwan is a part of China.

A. As

B. Which

C. That

D. What

答案：

(答案→)A. As

B. Which

C. That

D. What

解析：考查定语从句。As指代一句话内容，引导非限制性定语从句，位置很灵活，可以放在句首，句中，句末。Which引导的非限制性定语从句不能放在句首。That,what不能引导非限制性定语从句。故A正确。