is known to everybody the moon travels round the earth once every month.A. ItB. AsC. That

问题补充：

is known to everybody, the moon travels round the earth once every month.

A. It

B. As

C. That

D. Which

答案：

A. It

(答案→)B. As

C. That

D. Which

解析：考查定语从句。本题考查了非限制性定语从句，as指代后面一句话的内容在句中做主语。It,that不能引导非限制性定语从句;which引导的非限制性定语从句不能放在句首。句意：众所周知，月亮一个月绕地球一圈。故B项正确。