__is known to everybody,the moon travels around the earth once erver month,

问题描述:

__is known to everybody,the moon travels around the earth once erver month,
为什么不能用it呢?it 做形式主语,后边是真正得主语

as is known to everyboby 意思是:众所周知的;=it is well-know
如果用it 做形式主语的话,句子应该改为:
it is known to the moon travels around the earth once erver month.