指天气、季节、时间、距离、环境等 It is early spring, but it is already hot.现在是初春，但是天气已经很热了。 代替前面提过的事物、群体、想法、内容等或代替指示代词 Although he didn't like it, I decided to see the movie anyway.

尽管他不喜欢看这部电影，但我还是决定去看一看。 指不知性别的孩子和婴儿或不明确的人(由于某种原因而不知对方是谁) What will you call it if it is a boy?

要是男孩的话，你会给他取个什么名字？ 　　

　　2.it作形式主语或形式宾语

常用句型 it作形式主语 It is a pity/shame that ...　　　　 真可惜......

It is no wonder that ... 难怪......

It seems/appears that ... 似乎/看来......

It looks/seems as if/as though ... 看起来好像......

It happens that ... 碰巧......

It occurs to/comes to/strikes/hits sb.that ...

某人突然想起......

It is said/reported that ... 据说/据报道......

It is certain that ... ......是一定的

It is no use/good doing ... 做......没有用/好处

It takes sb.some time to do ... 做......花费某人若干时间 it作形式宾语 ①主语＋think/believe/suppose/consider/feel/make/keep ...＋it＋adj./n.＋for/of sb. to do/that从句

②主语＋think/believe/suppose/consider/feel/make/keep ...＋it＋useless/worth/worthwhile/no use/no good/a waste of time/money/energy ... ＋doing ... 　　

　　3．it的常用短语或句型

　　make it　　　　　　　　　　 获得成功；赶上

　　See to it that ... 确保......

　　count on/rely on/depend on it that ...　 相信......

　　as someone puts it 像某人所说的那样

　　When it comes to ... 当涉及/谈到......

　　I can't help it (...) (......)我没办法/情不自禁

I take it that ... 我理解的是......