is known to everybody，the moon travels around the earth once every month.
A. It
B. As
C. That
D. What
网友回答
A. It
B. As
C. That
D. What
解析：B
解析 本题考查as引导的非限制性定语从句。as作“正如……”解时，引导的非限制性定语从句来修饰整个句子，可前指或后指，此处为后指。当as在从句中作主语时，常用于下列短语：as is known，as is said，as is reported，as is announced等。