is well-known to all the great changes have taken place in China.A. ItB. thatC. AsD. Whic

问题补充：

is well-known to all, the great changes have taken place in China.

A. It

B. that

C. As

D. Which

答案：

A. It

B. that

(答案→)C. As

D. Which

解析：考查定语从句。此处有逗号隔开，此句子不是形式主语的句式，前面的句子修饰后面的句子构成一个非限制性定语从句，as可以放于句首，意思“这一点”来指代后句。