is known to everybody the moon travels around the earth once a month. .A. ItB. AsC. That

问题补充：

is known to everybody, the moon travels around the earth once a month. .

A. It

B. As

C. That

D. What

答案：

A. It

(答案→)B. As

C. That

D. What

解析：考查定语从句。As指代后面一句话的内容，引导非限制性定语从句，在本句总做主语。句意：正如每个人都知道的那样，月球一个月绕着地球一圈。故B正确。