it用法完全归纳一、it 作人称代词的用法1. 指事物作为人称代词，it 可以除人以外的一切事物或动物。
如：I dropped my watch and it broke. 我把手表掉在地上摔坏了。
It’s hard work, but I enjoy it. 工作很辛苦，可是我乐意干。
“Where is the dog?” “It’s in the bedroom. ” “狗在哪?”“在卧室里”。
2. 指人it 指人主要用于指不性别不明的婴儿或用于确认某人的身份。
如：Is it a boy or a girl? 是男孩还是女孩?There is a knock on the door. It must be the postman. 有人在敲门，一定是邮递员。
【说明】在答语中，常用来指本人，如说It’s me。
3. 代替某些代词代词it 还可用于代替指示代词this, that 以及复合不定代词something, anything, nothing等。
如：“What’s this?” “It’s a new machine. ” “这是什么?”“是一种新机器”。
Nothing is wrong, is it? 没出什么问题，是吗?二、it 作非人称代词的用法1. 基本用法it 作非人称代词的用法，主要用于指时间、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. 这里有时会很热。
2. 用于某些句型It’s time for sth. 该做某事了。
It’s time to do sth. 该做某事的时候了。
It’s time for sb to do sth. 某人该干某事了。
It’s (about / high) time + that-从句. 某人该做某事了。
(从句谓语用过去式，有时也用“should+动词原形”)It’s first (second) time + that-从句. 某人第几次干某事。
(从句谓语用现在完成时)It’s + 时间段+ since-从句. 自从……有一段时间了。
It’s a long time since he studied English 他好久没学英语了。
It’s + 时间段+ before-从句. 过多长的时间才……It's 9 o'clock before I went to bed.在我睡觉之前就是9点了。
三、it用作形式主语1.基本用法当不定式、动名词、从句等复杂成分用作句子主语时，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 wor k climbing mountains. 爬山是费劲的事。
It’s unknown when he will come. 他什么时候来还不知道。
2.用作形式主语的的重要句型(1) It + 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。
【说明】介词of 与for 的区别是：of 用于指某人的性格、属性、特征等，介词for表示对象，意为“对……来说” (from )。
(2) It takes sb + 时间段+ to do sth. 某人做某事花了……时间It takes years to master a new language. 要花多年的时间才能掌握一门新的语言。
【说明】此句型可以有以下多变种变体：It took me an hour to write the letter. =The letter took me an hour (to write). =I took an hour to write the letter. 我写这封信花了一个小时。
(3) It is up to sb. to do sth. 该由某人做某事It’s up to you to make the choice. 得由你来作选择。
(4) I t look (seem, appear, happen, occur) that [as if]… 似乎……It seemed as though he didn’t recognize me. 他似乎没认出我来。
It happened that I was out when he called. 他打电话时我碰巧不在家。
(5)If it were not for… / If it hadn’t been for… 若不是因为……If it were not for their help, we couldn’t have got over the difficulties. 要不是他们帮助，这些困难我们不克服不了的。
四、it用作形式宾语1. 基本用法当不定式、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。
Rumor has it that the defence minister will soon resign. 据传闻，国防部长不久就要辞职。
【说明】能用于此结构的动词不多，常见的有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 appreciate 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，好就太好了。
【说明】能用于此结构的动词不多，常见的有enjoy, hate, love, like, dislike, appreciate, prefer 等。
(3)动词+ prep + 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。
【说明】能用于此结构的动词不多，常见的有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. 多亏有你我才仍然活着。
I took it for granted that he would help us. 我认为他会帮助我们的。
【说明】能用于此结构的动词不多，常见的有take it for granted, bring it to sb’s attention, owe it to sb. 等。
五、考查it 在强调句中的用法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. 他是昨天结婚的。
It was a computer that he bought last week. 他上个星期买的是一台电脑。
【特别提醒】对于强调句的复习要特别注意两种情形：1.当强调句有插入语或复杂修饰语时：It was lack of money, not of effort, that defeated their plan. 他们的计划受挫，原因是缺少钱而不是没有尽力。
It was more in sorrow than in anger that he criticized his former colleague. 他批评以前的同事，并非出于气愤而是为他惋惜。
2.当强调为特殊疑问句时：Who was it that won the World Cup in 1982? 谁赢得了1982年的世界杯?How long ago is it that you last saw her? 你上一次看见她是多久以前的事？。