问题补充:
is known to everybody,the moon travels around the earth once every month.
A. It
B. As
C. That
D. What
答案:
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。