1、
It + be + 名词 + that从句：It is a fact that 事实是。
It is an honour that 非常荣幸。
It is common knowledge that …是常识。
It is a pity that 遗憾…… 。
2、
It + be + 动词的过去分词+ that从句。
It is said that 据说。
It is reported that 据报道。
It has been proved that 已经证明。
It is believed that … 人们认。
It is supposed that… 据猜测，
3、
It + 不及物动词（vi） + that 从句。
It seems that 似乎。
It happened that 碰巧。
It appears that 似乎。
4、
It is natural that… 很自然…。
It is strange that… 奇怪的是… 。