22-2 it作非人称代词的用法

1.用来指时间、距离、价值、天气、气候、温度等自然现象

it作非人称代词，主要用来指时间、距离、价值、天气、气候及温度等自然现象。如：

It's too late to go there now.现在去那儿已经太迟了。

It rained all day yesterday.昨天下了一天的雨。

It can get very hot here.这里会变得很热。

2.用于一些表示时间的固定句型

（1）It's time for sth.该做某事了；是做某事的时间了。如：

It's time for lunch.该吃午饭了。/是吃午饭的时间了。

（2）It's time to do sth.该做某事了；是做某事的时候了。如：

It's time to go to bed.该睡觉了。/是睡觉的时间了。

（3）It's time for sb.to do sth.某人该干某事了。如：

It's time for me to go home.我该回家了。

（4）It's time+that-从句.某人该做某事了。如：

It's time that you should do cleaning.你该去打扫卫生了。

（5）It's the first （second）time+that-从句。那是某人第几次干某事。如：

It is the first time that I have received your letter.那是我第一次收到你的来信。

（6）It's+时间段+since-从句。……多长时间了。如：

It's three years since he joined the Party.他入党三年了。

（7）It will be+时间段+before-从句。过多长的时间才……。如：

It will be hours before he arrives.再过几个小时他才到。

3.用作形式主语

（1）当动词不定式、动名词、从句等复杂成分作句子主语时，为保持句子平衡，通常把真正的主语放在句末，而在句首使用形式主语it。如：

It's very important to remember this.记住这一点很重要。

It's hard work climbing mountains.爬山是艰苦的工作。

It's unknown when he will come.他什么时候来还不知道。

（2）it用作形式主语的重要句型

①It+be+adj.for （of）sb.to do sth.某人做某事……

It is hard for him to make up his mind.他很难下定决心。

It was foolish of her to say such a thing.她说那样的话，真是太蠢了。

注意：

介词of与for的区别是：of用来指某人的性格、属性、特征等，介词for表示对象，意为“对……来说”。

②It takes sb.+时间段+to do sth.做某事需要某人……时间。如：

It takes us years to master a new language.掌握一门新的语言需要我们多年的时间。

③It is up to sb.to do sth.该由某人做某事。如：

It's up to you to make the choice.得由你来作选择。

④It seems （look，appear，happen）that/as if ...似乎……

It seems that he is always correct.他好像总是对的。

It happened that I was out when he called.他打电话时我碰巧不在家。

⑤It is said（reported/believed）that ...据说（据报道/人们相信）……。如：

It is said that he has joined the Party.据说他入党了。

It's reported that Chinese spend more than 40 minutes a day reading WeChat.据报道中国人每天花40多分钟看微信。

It is believed that the book is well worth reading.人们相信那本书很值得一看。

4.用作形式宾语

（1）当动词不定式、动名词、从句等复杂成分用作宾语且其后跟有宾语补足语时，通常会在宾语补足语前使用it作为形式宾语，而将真正的宾语移至句末。其基本结构为“动词+it+宾语补足语+不定式（动名词或从句）”。如：

I find it difficult to do the job well.我发现做好这件事不容易。

I think it best that you should stay here.我认为你最好住这儿。

We think it no use complaining.我们认为抱怨是没有用的。

（2）用作形式宾语的几个特殊结构

①动词+it+that-从句。如：

I like it that you came.你来了，我很高兴。

I take it （that）he will come on time.我认为他会准时来的。

You can put it that it was arranged before.你可以说这是以前安排的。

注意：

能用于此结构的动词主要有have，take，put，like等。

②动词+it+when （if）-从句。如：

I dislike it when you whistle.我不爱听你吹口哨。

We really appreciated it when she offered to help.她来帮忙了，我们十分感激。

I'd prefer it if I didn't have to do so much work.要是我不必做那么多工作，那就太好了。

注意：

能用于此结构的动词主要有enjoy，hate，love，like，dislike，appreciate，prefer等。

③动词+介词+it+that-从句。如：

See to it that you're not late again.注意千万不要再迟到。

Look to it that this doesn't happen again.注意不要再发生这种事。

You may rely on it that he'll come to meet you.你放心，他会来接你的。

I can't answer for it that he will come.我不能保证他会来。

注意：

能用于此结构的动词主要有see to，look to，insist on，stick to，depend on，answer for等。

④动词+it+介词短语+that-从句。如：

I owe it to you that I am still alive.多亏有你，我才活下来。

I took it for granted that he would help us.我认为他会帮助我们的。

注意：

能用于此结构的动词主要有take it for granted，bring it to sb's attention，owe it to sb.等。

5.用于强调句中

强调句的基本结构是：It+be+被强调部分+that （who）+其他部分。如：

It was yesterday that he got married.他是昨天结的婚。

It was a computer that he bought last week.他上个星期买的是一台电脑。

Who was it that won the World Cup in 2016？谁赢了2016年的世界杯？