is known to us the 16th Asian Games will be held in Guangzhou China in November .A

问题补充：

is known to us, the 16th Asian Games will be held in Guangzhou, China in November, .

A. As

B. It

C. Which

D. What

答案：

(答案→)A. As

B. It

C. Which

D. What

解析：句意：我们都知道16届亚运会将在11月份在中国的广州举行。这里使用as引导非限制性定语从句，指代后面的句子，as在定语从句中做主语，it可以做形式主语，那么后面应该是that引导的主语从句，which引导非限制性定语从句的时候，不能在句首，what引导的是主语从句，所以选A。