It在初中阶段的用法
在初中英语教材中，出现了许多it的用法，现归纳如下
1、用作人称代词，代替前文提到过的事物。

用于同名同物的场合。

My watch is missing. I can’t find it anywhere.(it=my watch)
2、代替指示代词that或this。

What’s this? It’s a computer. What’s that? It’s a pen.
3、用作非人称代词，表示时间、天气、距离、潮汐、自然环境等。

It’s t ime for lunch. It was a raining day.
How far is it from your office to the bank?It was very quiet in the library It will be lovely in the garden tonight.
4、用于指代性别不详的人或动物，有时指婴、幼儿。

--Who is it? 谁(敲门)啊? --It’s me , Lucy.
Her new baby is tiny. It only weighs two kilos.
5、用作指示代词，指代前文已提到或后文将提到的事情。

You have saved my life; I’ll never forget it.
The statesman was murdered last night. It was a terrible blow to the people.
6、用作引导词(即先行代词)，在句中作形式主语或形式宾语，代替后面的动词不定式短语、动名词短语、从句，或引导强调结构。

(1)代替动词不定式(短语)。

It is necessary for him to go there.(由for引出动词不定式的逻辑主语) It’s very good of you to have listened to me.(由of引出动词不定式的逻辑主语)
Don’t you consider it better not to disturb him now?
(2)代替动名词短语，作主语或宾语。

It’s no use talking to him about it.
I found it necessary discussing the problem.
.(3)代替由从属连词that引导，或由连接代词及连接副词引导的从句，在句中作主语或宾语。

It was evident that victory had returned.
They want to make it clear to the public that they do an important and necessary job.
(4)用在强调结构中，表示所强调的内容。

It is the people that (who) are really powerful.
It was on Sunday night that all this happened.
典型考题
1.---This is my dog,Spotty. ---Oh,________is very lovely.
A it
B this
C that
2.--- is very important that you told him
3.A it B this C that。