China is a country with the largest population in the world we all know it.A. andB. which

问题补充：

China is a country with the largest population in the world, we all know it.

A. and

B. which

C. that

D. as

答案：

(答案→)A. and

B. which

C. that

D. as

解析：句意：中国是世界上人口最多的国家，我们都知道这一点。we all know it.是完整的句子，所以不是定语从句，不能填which或as，that不能连接两个并列句，所以选A。