___is known to everyone，the moon travels

Question

___is known to everyone，the moon travels round the earth once every month.
A.It B.As
请选择正确的答案并说明理由，有理由才能采纳！

Answer 1

As 因为前后句是从句和主句的关系。在英语中，想让两个句子连接的话必须要用连词。
如果你填it 的话，那么两个句子就没有连词了，句子不成立。
as在这个句子里既充当连词，又充当从句的主语。
as 就有这个用法：as is known to everyone 众所周知

Answer 2

As追答

As 有链接句子的作用

It is known to everyone 感觉在这里句子就可以停了

如果这样的话需要一个 that

It is known to everyone that

但是没有。 另外一个选项是

像大家都所知道的, ...