1、it的用法归纳it既可以用作代词，也可以用作引导词（作形式主语或形式宾语），还可以用来构成强调句型。一、用作代词这是it的基本用法。1. 指事物-指代上文或刚提到的事物，以避免重复。I dropped my watch and it broke. 我把手表掉在地上摔坏了。 Its hard work, but I enjoy it. 工作很辛苦，可是我乐意干。 “Where is the dog?” “Its in the bedroom.” “狗在哪?”“在卧室里”。Shanghai is a beautiful city, isnt it?2. 指人-指代未知性别的婴儿或身份不明确的人。
2、-Is this your dog？-No, it isnt.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. Someone is knocking at the door. Who can it be? 【说明】在答语中，常用来指本人，如说 Its me。3. 代替某些代词。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：“Whats this?” “Its a new machine.” “这
3、是什么?”“是一种新机器”。 Nothing is wrong, is it? 没出什么问题，是吗?4. 指抽象事物:It was a great surprise to me when he did a thing like thatYouve helped me a lot. I shall never forget it.I tried my best to persuade him to give up smoking, but it didnt help. 辨析 代词it ,one 和that.（1）it代替的是前面提到的同一名称的同一事物，即同名同物。所代替的名词可以是可数名词也可
4、以是不可数名词。 （2）one代替的是前面提到的同名异物中的任何一个，所代替的上面可数名词，其前可带冠词与修饰语，如代替复数名词，则用ones。 （3）that 代替前面提到的同名异物中特指的事物，所代替的名词可以是可数名词也可是不可数名词，但其前通常不能有修饰语。The population problem may be the greatest one in the world. The doctor in our school is younger than that_ in your school.I bought a dictionary three years ago and I
5、am still using it_ now.I bought a dictionary three years ago but I am going to buy a new one_ soon.5 it有时并不指具体的东西，而泛指天气、日期、时间、温度、价值、路程距离、环境、自然现象等，称为非人称的代词it。It is a lovely day, isnt it?(天气)It is April First today. (日期)It was nearly midnight when she came back.（时间）It was very quiet in the caf. （环境）It
6、 is half an hours walk to the city centre. (距离)It is three dollars. (价值）Today it is 30 degrees centigrade. (温度)三、做形式主语(一)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，这样可以使句子避免 “头重脚轻”。如：Its very important to remember this. 记住这一点很重要。Its hard work climbing mountains. 爬山是费劲的事。Its unknow
7、n when he will come. 他什么时候来还不知道。（二）用it做形式主语的基本句型1. It is time( for sb) to do sth./介词短语。“是(某人)该干某事的时候了” -（初中学过） It is time to have supper/for supper.2. It is ones turn to do sth.意为轮到某人做某事了。-（初中学过）Its your turn to be on duty tomorrow. 明天轮到你值日了。3. It takes sb. some time to do sth. -（初中学过）该句型中的不定式是真正的主语
8、，it是形式主语，句型中的直接宾语是时间。常译为“做事情要花费某人时间”“某人花了多少时间做某事”It took thousands of people many years to build the Great Wall.4. It+ is/has been +一段时间+since从句. -（初中学过） 关于该句型详解见下面第11条。5. It is/ was +过去分词+ that从句.1) It is said (reported，learned/ believed/ thought / considered/well-known .) that从句。该结构常译为据说（据报道，据悉）。I
9、t is said that he has come to Beijing.It is reported that another earth satellite has been put into orbit.2) It is suggested (ordered /demanded/insisted/commanded.) +that从句。该句型和上一句属一个句型。主句中的过去分词是表示请求、建议、命令( 一坚持，二命令，三建议,四要求)等词时，that后的从句要用虚拟语气（should+动词原形）。should可以省略，常译为“据建议；有命令”It is suggested that t
10、he meeting (should) be put off.It was ordered that we (should) arrive there in two hours.6. It is a pity ( a shame . ) that从句 . 在该句型中，that后的从句 （1）一般用虚拟语气（should+动词原形），should可以省去，表示出乎意料，常译为“竟然”。（2）没有这种意义时，则不用虚拟语气。It is a pity that such a thing (should) happen in your class.这种事竟然发生在你们班上，真是遗憾。It is a p
11、ity that he is ill.他生病了，真遗憾！7. It is no use doing sth 做某事是没有用的该句型中的真正主语是动名词短语，主句中的表语可以是 no good (not any good), no use (not any use ), no pleasureIt is no good learning English without speaking English.It is no use crying over the spilt milk.It is no pleasure looking through these any longer. 8. It
12、is the first (second .last) time that sb. has done sth.该句型应和下一个句型区别开来。该句型表示截止到说话时某人的一种经历，不用虚拟语气，而用完成时态。如果主句谓语动词是is，从句用现在完成时态；如果主句谓语动词是was，从句则用过去完成时态。该结构中that可以省去；it有时也用this/that替换，常译为“是某人第一（二,）次做某事”。It is the first time that I have enjoyed this kind of moon cake.This was the second time that I had b
13、een to Beijing.9. It is (about/high ) time that .sb. did sth / sb. should do sth.该句型中that 后的从句应该用虚拟语气，值得注意的是：（1）常用过去时态表示虚拟(2)有时也用should + 动词原形，should 不能省，常译为是（正是）的时侯了 “早就到了时候了”。It is time that children should go to bed.=It is time that children went to bed.10It is/ was + adj.+ for /of+ sb. +to do st
14、h. -（初中学过）该句型中的不定式短语是真正主语。(1)如果句子中的形容词是修饰逻辑主语sb.的，描述sb.“（真）是（太）了”，这时用of引出逻辑主语。这里的形容词通常是表示人的性格、品质、特征等。常见的这类形容词有：bad, brave, careless, clever, cruel, foolish ,honest, kind, lazy, modest, naughty, polite, rude, silly, stupid ,wise ,wrong等。该句型可以换成Sb.+be+adj.+to do sth.It is kind of you to say so = You a
15、re kind to say so.(2)如果句子中的形容词是修饰to do sth.不定式的，说明“做某事是的”，这时用for 引出 逻辑主语sb。这里的形容词通常是表示难、易、重要性、必要性、紧迫性、危险等情况的词。常见的这类形容词有：hard, difficult, easy, important, useful, necessary, natural, safe, common , normal, dangerous, unusual, great, impossible等。It is useful for us to learn English well. 11. 与it 有关的几个
16、时间状语从句（1）It+ is/has been +一段时间+since从句. -（初中学过） 该句型主要用作处理瞬间动词的完成时，要和表示一段时间的时间状语连用。主句中的“一段时间”作表语，其时态是一般现在时或现在完成时，引导的从句通常是一般过去时态，而且是瞬间动词。（如果主句是一般过去时，从句则用过去完成时。）It is /has been 5 years since his father died.It is / has been four days since I caught a cold. It is almost five years since we saw each othe
17、r last time. Its ages since we last met.（2）It +be + not long/ long / 一段时间+ before 从句 该句型主句中的it指时间，主句中的时态常是一般将来时或一般过去时两种时态。主句中的谓语动词和从句中的谓语动词在时态上一般是一致的，既：主句中be动词是was时，从句用一般过去时。 主句中be动词是will be时，从句用一般现在时代替将来时。主句中的表语多是long ,not long ,3 days, 2 weeks等表示时间段的词和短语。常译为“之后才”，“没过就”It was 3 days before he went
18、to Beijing. It was not long before he left Nanjing.It will not be long before he finishes his job. （3）It + be + 时间点 + when从句这个句型中, it 指时间，而且表示时间的词语前没有介词(时间一般为具体时间)。主句中的谓语动词和从句中的谓语动词在时态上一般是一致的，既：主句中be动词是was时，从句用一般过去时。 主句中be动词是will be时，从句用一般现在时代替将来时。常译为“当的时候，是”It was already 8 oclock when we got home.
19、It was the next morning when we finished our work. It was eight oclock when we arrived.It will be midnight when they get there.12. It is clear ( obvious， true， possible， certain.)+ that从句该句型中it 是形式主语，真正的主语是that 引导的主语从句，常译为很清楚（显然，真的，肯定）是主语从句最常见的一种结构。 Its clear that smoking is bad for our health.13. I
20、t is important ( necessary，strange，natural.) +that从句该句型和上一个同属一个句型；由于主句中的形容词不同，that 后的从句中要用虚拟语气（should + 动词原形），should 可以省去。It is important that we (should) learn English well.It is necessary that he (should) remember these words.14. It is a waste of time /money doing sth. “做某件事是浪费”Its a waste of time
21、 your talking to him. 你和他谈是浪费时间。15. (It is) no wonder (that) 难怪Its no wonder he is not hungry; he has been eating sweets all day. 难怪他不饿，他整天在吃糖果。16. It is up to sb. to do sth. 该句型为“该由某人负责做”，该句型中up后的to是介词。It is up to him to clean our classroom today.Its up to you to to make the choice. 17. It seems/se
22、emed（似乎）that从句-（初中学过）It appears（似乎）that从句It happens(碰巧)that从句该句型中的it 是形式主语，that 引导的是主语从句，主句中的happen, seem等词是不及物动词。It happened that he met his teacher in the street. (碰巧)It seems that he will be back in a few days. (看来)The Foreign Minister said, “It is our hope that the two sides will work towards pe
23、ace.” 18. It looks (seems) as if 该句型中it 无意义。as if 引导一个状语从句，常译为：“看起来好像”如果与事实不相符合，则用虚拟语气。It looks as if he is ill. （真的病了）陈述语气It looks as if he were ill. （事实上没有生病）虚拟语气It seemed as if he was dying.19. Itsto do sth.。-（初中学过）Its a good idea to go out for a walk. 出去散步是个好主意。四、做形式宾语 （一）基本用法当不定式、动名词、从句等复杂成分用作宾
24、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。I find it hard to give up smoking. He feels it his duty to help others.【小结：
25、 6123口诀 】-“6个动词（find, make, feel, think, believe, consider），1个形式宾语（it），2个宾补（adj, n.），3个真宾语（to do sth. doing sth. that从句）。【另外注意】it做形式宾语的三类特殊句式1，动词+it+if/when 从句。 I would appreciate it if you could give me some advice.说明 能用于此结构的动词不多，如appreciate, hate, enjoy, like, dislike, love, prefer等。2，动词+介词+it+tha
26、t从句。Ill see to it that all these letters will be sent to the post office before twelve.说明 能用于此结构的动词不多，能用于此句型的动词短语有depend on, rely on, count on , see to, insist on, stick to,等。3. 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
27、认为他会帮助我们的。Dont bother to arrange anything. Just to leave it to me to sort out. 说明 能用于此结构的动词不多，常见的有take it for granted认为想当然；bring it to sbs attention, owe it to sb把归功于；leave it to sb. that把留给某人去做；keep it in mind that记住等。五、it 用于强调句句型：“It is/was +被强调部分 +that/ who +其他部分”。 it可以用来对句子的某一成分加以强调（对主语、宾语、状语等进行
28、强调；若要强调谓语，则要用do, does, did）。 例如对下面句子的各个成分进行强调：Tom saw your sister in Beijing last week. It was Tom who saw your sister in Beijing last week. It was your sister who Tom saw in Beijing last week. It was in Beijing that Tom saw your sister last week. It was last week that Tom saw your sister in Beijing
29、. （Tom did see your sister in Beijing last week.） 【注】在对时间状语not until结构强调时，必须把not与until一起放到被强调的位置上。既：it is /was not until that.(1)I didnt recognize her until she took off her dark glasses. It was not until she took off her dark glasses that I recognized her. (2)I didnt go to bed until twelve oclock l
30、ast night. It was not until twelve oclock last night that I went to bed.六、与it有关的常用固定搭配 1. make it 在口语当中相当于succeed,表示：成功、做到、说定、赶上、及时到达 。She feels shes finally made it as a singer.Im afraid I cant walk any further. Come on! You can make it.If we set off now, we should make it to the station before the
31、 train goes. 2. make it+时间点 表示“就约定在什么时候了”when shall we meet tomorrow morning.lets make it 8:00 at the school gate. 3. （1）take it/things easy别紧张（2）believe it or not（3）when it comes to 一谈到;就.而论（4）Forget it.没关系；别在意；算了吧。（5）It/That ( all/just ) depends. 要看情况而定。 （6）It doesnt matter 通常用来回应别人的道歉. （Never min
32、d 别在意,通常是在别人有过失时让别人不要在意,是种安慰性的话）（7）Thats it.（口语）完了；没有了（表示某个情况已经结束）；做得对。4. It makes no/much difference没有/有区别Its doesnt make much difference my being there. 我在不在那儿没有什么影响。 高中英语It的用法专项练习题1. Was it during the Second World War_ he died? A.that B.while C.in which D.then2. Is _ necessary to complete the des
33、ign before National Day?A.this B.that C.it D.he3. I dont think _ possible to master a foreign language without much memory work.A.this B.that C.its D.it4. Does _ matter if he cant finish the job on time?A.this B.that C.he D.it5. It was not _ she took off her glasses _ I realized she was a famous fil
34、m star.A.when, that B.until, that C.until, that D.when, then6. I was disappointed with the film. I had expected _ to be much better.A.that B.this C.one D.it7. It was not until 1920 _ regular radio broadcasts began.A.while B.which C.that D.since8. _is a fact that English is being accepted as an inter
35、national language.A.There B.This C.That D.It9. It was only when I reread this poems recently _ I began to appreciate their beauty.A.until B.that C.then D.so10. I hate_when people talk with their mouths full.A.it B.that C.these D.them11. It is the ability to do the job _ matters not where you come fr
36、om or what you are.A.one B.that C.what D.it12. I like _ in the autumn when the weather is clear and bright.A. this B. that C. it D. one13. Do you like _ here?Oh, yes. The air, the weather, the way of life. Everything is so nice. A. this B. These C. That D. it14. We needed a new cupboard for the kitc
37、hen. So Peter made _ from some wood. A. it B. One C. Himself D. another15. The foreign Minister said, _ our hope that the two sides will work towards peace. A. This is B. There is C. That is D. It is16. _ is reported in the newspaper, talks between the two countries are making progress.A. It B. As C
38、. That D. What17. How often do you eat out? _, but usually once a week.A. Have no idea B. It depends C. As usual D. Generally speaking18. We wanted to get home before dark, but it didnt quite _ as planed.A. make out B. turn out C. go on D. come up19. What do you want to do next? We have half an hour
39、 until the basketball game._. Whatever you want to do is fine with me.A. It just depends B. Its up to you C. All right D. Glad to hear that20. It was _ back home after the experiment.A. not until midnight did he go B. until midnight that he didnt goC. not until midnight that he went D. until midnight when he didnt go 参考答案： 1-5 ACDDB 6-10 DCDBA 11-15 ACDBD 16-20 BBBBC
