1、it 作形式主语和形式宾语it 既可作人称代词，用来表示动物或无生命的物体等，也可以作无人称代词，在句中作主语，表示“时间”、“距离” 、“ 天气”等。它还可以引导强调句，使语气得以加强。此外，it 在句中能作引导词，充当句子中的形式上的成分，如形式主语、形式宾语等。 it 作形式主语：it 作形式主语时没有具体的意义，而只是帮助把真正的主语移到句子后部去，使句子显得平稳一些。it 作形式主语时，可以代替三种形式：不定式、动名词和主语从句。1. it 代替不定式短语常用于下列句型中：It + be +形容词 + (for/of sb.) to do sth.It + be + 名词 + to
2、do sth.It takes sb. some time to do sth. 干花了某人时间Its up to sb. to do sth. 干 是某人的职责或义务如：It is everyones duty to obey the law.遵守法律是每个人的义务。（ it 作形式主语, 代替不定式短语 to obey the law）It is difficult for a foreigner to learn Chinese.对于一个外国人来说，学习汉语是困难的。（ it 作形式主语, 代替不定式短语 to learn Chinese）It is not right to use t
3、hese places as rubbish dumps.把这些地方用来倒垃圾是不对的。（it 作形式主语, 代替不定式短语 to use these places as rubbish dumps）It took them a year to build the bridge.建这座桥花了他们一年的时间。（ it 作形式主语, 代替不定式短语 to build the bridge）It is bad manners to stare at people.瞪着眼睛看人是不礼貌的。（ it 作形式主语, 代替不定式短语 to stare at people）It is up to us to
4、help those in need. 帮助那些有困难的人是我们的责任。（ it 作形式主语, 代替不定式短语 to help those in need）It is not up to you to tell me how to do my job. 我怎样干我的工作不用你来多嘴。（ it 作形式主语, 代替不定式短语 to tell me how to do my job） It be + 形容词 + for sb. to do sth.与 It be + 形容词+of sb. to do sth.：如果句型中的形容词描述的是 sb.的品质、品格，在逻辑上可以作 sb.的表语，则 sb.前
5、应用介词 of，否则就用 for。如：Its necessary for us to use a short-wave radio to pick up the programmes.我们用一台短波收音机收听这些节目是必要的。Its important for us to learn English well.学好英语对我们来说是重要的。Its kind of you to help me.感谢你对我的帮助。（= You are kind to help me. ）It was foolish of him to give up the job.他放弃那工作是愚蠢的。（= He was foo
6、lish to give up the job.） it 代替动名词短语：动名词作主语用后置形式的情况远不及不定式那么普遍，常限于 no good, no use, useless, waste 等词的后面。 It is no good/ use having a car if you cant drive. 如果你不会开车，有车也没用。( it 作形式主语,代替动名词短语 having a car)It is a waste of time watching TV.看电视是浪费时间。（ it 作形式主语,代替动名词短语 watching TV）It is no use asking him.
7、问他没有用。（ it 作形式主语,代替动名词短语 asking him）It is no use talking to him about it.和他谈这事没有用。（ it 作形式主语,代替动名词短语 talking to him about it） it 代替主语从句：这个主语从句可以用连词 that 引导，也可以用连接代词或连接副词引导。如：It was clear that they had no desire for peace.很清楚他们没有和平的诚意。（ it 作形式主语,代替主语从句 that they had no desire for peace）It is doubtful
8、 whether she will be able to come.她能否来还很难说。（ it 作形式主语,代替主语从句 whether she will be able to come）It was clear enough what she meant.她的意思是够清楚的。（ it 作形式主语,代替主语从句 what she meant）It hasnt been made clear when the new road is to be opened to traffic.还没明确宣布新路什么时候通车。（ it 作形式主语,代替主语从句 when the new road is to b
9、e opened to traffic）It is a mystery to me how it all happened.这都是怎么发生的对于我来说还是一个谜。（ it 作形式主语,代替主语从句 how it all happened）用 it 作形式主语，把真正的主语从句移至后面的常见句型有： It is a pity/ a shame/ a fact/ an honour/ good news/ no wonder/ a wonder that如：It was a pity that the engineer couldnt come.可惜工程师没能够来。It is a wonder t
10、hat he continues to gamble when he always loses!令人惊讶的是他一直输还一直赌。（It is）no wonder (that) you were late!难怪你来晚了。It is a shame that the rain spoiled our picnic. 真可惜，这场雨把我们的野餐给搅了。It is a fact that English is being accepted as international language.英语被认为是国际语言，这是一个事实。 It is + 形容词（如： strange/ natural/ surpr
11、ising/ obvious/ true/ fortunate/ wonderful/ funny/ possible/ impossible/ likely/ unlikely/ clear/ unusual/ certain/ important）that 如：It is certain that he will win.他一定会取胜。It is important that we should learn from each other and help each other.我们应当互相学习，互相帮助，这是很重要的。It was obvious that the child had b
12、een badly treated.很显然那个孩子受过虐待。It is likely that he will ring me tonight. 他今晚可能给我打电话。It is strange that he should have left without telling us. 真奇怪，他也没说一声就走了。It is unlikely that their group will get ahead of us. 他们小组不会赶到我们前头去。 It seems/ happened/ turned out/ suddenly struck me/ occurred to methat 如：I
13、t happened that I wasnt there that day. 恰好那天我不在那里。It seems that his idea is more practical.看起来他的意见更实际一些。It suddenly occurred to me that I knew how to solve that problem.我忽然想起我知道怎样解决那个问题。 It + be + 过去分词（如：said/ reported/ announced/ decided/ expected/ hoped/ known/ believed）that如：It is hoped that the
14、number of deer will greatly increase very soon.(相当于：People hope that the number of deer will greatly increase very soon)人们希望鹿的数目将会很快增加。It is said that nothing has been done about it. 据说至今对此没采取任何措施。It is reported that more than twenty people were killed in that bus accident.据报道在那次的公共汽车事故中有二十多人丧生。It i
15、s known that he is one of the best teachers in our school.大家都知道他是我们学校最好的教师之一。It is believed that the flood there is the biggest in 100 years.据认为那儿的洪水是百年来最大的洪水。* 注意要在 It is suggested/required/desired/ordered/proposedthat的主语从句中用虚拟语气：(should) + 动词原形如：It is requested that he give a performance at the pa
16、rty.有人请求他在聚会上表演一个节目。 It is suggested that we should get everything ready by tonight.建议一切在今晚准备好。It is ordered that the radio be sent there at once.据命令，这台收音机要立刻送到那里去。 It doesnt matter +连接代词或副词It doesnt make too much difference +连接代词或副词如：It doesnt matter whether he comes or not.他来还是不来都没关系。It wont make
17、much difference whether you go today or tomorrow.你今天去也好，明天去也好，关系不大。 it 作形式宾语：it 作形式宾语时，可以代替三种形式：不定式、动名词和宾语从句。it 作形式宾语时，需具备两个条件： 真正的宾语是不定式、动名词或从句 有宾语补足语具备了这两个条件，形式宾语 it 一定要用。1. it 代替不定式短语think/ find/ feel/ consider/ make/ regard+ it +形容词/名词 + 不定式短语如：I find it pleasant to work with him.(it 作形式宾语，代替不定式
18、短语 to work with him)我觉得和他一起工作很愉快。They felt it difficult to finish the work in such a short time.（ it 作形式宾语，代替不定式短语 to finish the work in such a short time）他们认为在这么短的时间内完成这项工作是困难的。She thinks it her duty to help us.（ it 作形式宾语，代替不定式短语 to help us）她觉得帮助我们是她的责任。I think it my honor to be invited to speak he
19、re.（ it 作形式宾语，代替不定式短语 to be invited to speak here）我觉得应邀在这儿演讲是我的荣耀。Tom didnt find it difficult to write letters in Chinese.（ it 作形式宾语，代替不定式短语 to write letters in Chinese）汤姆发现用汉语写信不难。All these noises made it impossible for me to go on with the work.（ it 作形式宾语，代替不定式短语 to go on with the work）这些噪音使我无法继续工
20、作。 it 代替动名词短语( 这只限于少数句型，在多数情况下用不定式时更多一些)如：The professor considers it no good reading without understanding.这位教授认为阅读而不理解没有益处。Do you consider it any good trying again?你觉得再试会有好处吗？He found it useless( no use) arguing with him.他发现和他辩论没有用。He thought it absolutely senseless attempting the impossible.想做不可能的
21、事情，他认为是完全没道理的。I dont think it worthwhile going to such a place.到这样一个地方去我看是不值得的。 it 代替宾语从句：如：We all thought it a pity that the conference should have been cancelled.会议取消了我们都感到很遗憾。I took it for granted that they were not coming. 我想他们准是不会来的了。Ill see to it that everything is ready in time. 我负责使一切都按时准备好。
22、 含 it 的常用句型英语中有一些固定句型中含有 it,应注意这些句型的使用。1. It be + 被强调部分 + that/ who + 其他成分强调句型可以强调一个句子的主语、宾语、表语及状语等成分。如果被强调的成分是表示人的词，可以用 that 或 who(whom)连接其他成分；被强调的成分是表示人以外的词，例如表示事物、时间或地点的词，用 that 连接其他成分。例如我们可以用强调句型强调下列句子的主语（如 ）、宾语（如 ）、地点状语（如 ）及时间状语（如 ）I met Peter in Japan last year. It was I who/that met Peter in
23、Japan last year. It was Peter whom/that I met in Japan last year. It was in Japan that I met Peter last year. It was last year that I met Peter in Japan.* not until 也可用于强调句型例 1 Mr Brown didnt come back until eleven oclock.可变为：It was not until eleven oclock that Mr Brown came back.例 2 The rain didnt
24、stop until midnight.可变为：It was not until midnight that the rain stopped.* 强调句也可变为特殊疑问句例 1 It was in 1949 that the PRC was founded.可变为：When was it that the PRC was founded?例 2 Your dad worked in this factory two years ago.可变为：Where was it that your dad worked two years ago?2Its + 地点状语+ that （强调句）Its
25、+地点名词+ where (定语从句)如：It is the town where I was born.(the town 为地点名词，定语从句)这是我出生的镇子。It was in the town that I was born.(in the town 为地点状语，强调句型)我出生在这个镇子。3.Its + 时间名词+ when(时间状语从句)Its + 时间状语 +that(强调句)如：It was at 8 oclock that he returned.(at 8 oclock 是时间状语，强调句)他是在八点钟回来的。It was 8 oclock when he returne
26、d.(8 oclock 是时间名词，时间状语从句) 他回来的时候是八点钟。4. if it is convenient to you 如果你方便的话如：If it is convenient to you, you can start tomorrow.如果方便的话，你明天可以动身。5. believe it or not 信不信由你如：Believe it or not, Ill go abroad next month.不管你信还是不信，我下个月要出国。Believer it or not, we were left waiting in the rain for two hours.信不
27、信由你，我们冒雨一直等了两个小时。6. Its time thatdid / should do (定语从句)如：It is time that I went and picked up my daughter from school.我该去学校接我女儿放学了。Its high time that we stopped/should stop this practice.我们的确该停止这种做法了。7. It is /has beensincedid(时间状语从句)如：It is just a week since we arrived here.我们来这里已一星期了。8.It wont be
28、before用不了（多长时间）就会It will bebefore得过（多长时间）才 It wasnt before没过（多长时间）就It wasbefore过了（多长时间）才如：It will be a long time before we finish the task.我们还需要很长时间才能完成这项任务。It wasnt long before he learned to use the computer.不久他就学会使用计算机了。It was some time before he told me about this affair.过了一段时间之后他告诉了我这件事。It wont
29、be long before we meet again.不久之后我们还会再见面的。 易混用其他句型英语中有一些句型不含 it, 但却易被误用了 it，常见的有以下句型： There is something/nothing wrong/ the matter with sb./ sth.如：There is nothing wrong /the matter with him. Hes just pretending.他没什么事，他只是在装呢。2.There is no doubt about对毫不怀疑There is no doubt that对毫不怀疑如：There is no doub
30、t about his suitability for the job. 毫无疑问，他适合这个工作。There is no doubt about the fact. 关于这个事实毫无怀疑。There is no doubt that he is hard to deal with. 毫无置疑他很难对付。 There is no need (for sb.) to do sth. 没必要如：There was no need for him to remain in Paris. 他没有必要继续留在巴黎。There is no need for you to start yet. 你现在还不必
31、动身。4.There is no/a possibility that 没可能/有可能(= It is impossible/possible that )如：There is a possibility that the train may be late. 可能火车要晚点。There is no possibility that well see him this weekend. 我们本周末不可能见到他。5.There is a chance that 可能如：There is a chance that the sick child will get well. 这个生病的孩子可能会好
32、起来的。6.There be no/ some differences betweenand和之间没/有区别如：There are some differences between the two languages. 这两种语言之间有些区别。7. After what seemed + 时间如：After what seemed a very long time, the wounded soldier came back to life.在经过似乎很长的一段时间之后，那个受伤的士兵苏醒了过来。8. There be difficulty/ trouble (in) doing sth. 干
33、有困难如：There was no difficulty in finding him.找到他没费什么事。习题演练：1._ is reported that he got seven gold medals.A. That B. Word C. It D. News2.How long _ to finish the work?A. you will take B. will you take C. you will take it D. will it take you3._ no need for us to discuss the problem again. It has alread
34、y been settled.A. It has B. There has C. It is D. There is4.I was disappointed with the play. I had expected _ to be much better.A. that B. this C. one D. it5.I dont think _ possible to master a foreign language without much memory work.A. it B. that C. its D. this6.Does _ matter if he cant finish t
35、he job on time?A. this B. it C. he D. that7.-Do you need my ruler?-No, thanks. Ive got _ myself.A. it B. each C. one D. the one8.-Which person do you mean?-_ who wears a new gold watch.A. The one B. One C. Each D. It9.It _ three years since I left England.A. has been B. was C. had been D. will be 10
36、.It wont be long _ the island _ to our motherland.A. when, returns B. before, will return C. since, returns D. before, returns11.How many years is it _ your family moved here?A. after B. since C. before D. until12._ is a pity that you forgot both her address and her telephone number.A. It B. There C
37、. This D. That13.I saw no more than one copy left in the bookshop. Will you go and buy _?A. it B. some C. any D. one14.Will you see to _ that the luggage is brought back?A. me B. yourself C. it D. them15.It _ that she has lost interest in studying English.A. seemed B. appears C. looks D. remains16._
38、 happened that I met one of my friends yesterday.A. I B. That C. It D. How17.I think _ right that you didnt tell him the bad news.A. it B. its C. you D. that18. _ to say which one I should choose.A. Thats hard B. It is hard C. There no use D. It no good19._ surprised me most was that she had become
39、a famous singer.A. That B. It C. What D. This20._ will take you a lot of time to find him in the crowd.A. It B. I C. We D. They21.He felt _ to work for human rights and progress.A. it his duty B. his duty C. that is a duty D. that is his duty22.People in the west makes _ a rule to buy Christmas pres
40、ents for their relatives and friends.A. that B. it C. this D. The thing23._needs further discussion whether well build a library or not.A. We B. He C. It D. The thing24._ is no good _ without doing anything.A. This, talking B. It, to talk C. It, talking D. That, to talk25._ is no difference between
41、them.A. There B. Where C. It D. What26.Was it _ that they saw?A. she B. that she C. her D. herself27._ being Sunday, the library was closed.A. That B. It is C. It D. This28.It was evening _ we arrived there.A. that B. when C. this D. since29.It was in the village _ now is a small town _ the earthqua
42、ke occurred.A. where, which B. which, where C. which, that D. that, where30.-Few children are as bright as he is, and also, he works very hard.-Its no _ that he always gets the first place in any examination.A. question B. doubt C. problem D. wonder答案与提示：1.C it 在此句中是形式主语，真正的主语是 that 从句。这个句型的结构是：it b
43、e +过去分词 +that 从句。2.D it takes sb. some time to do sth. 意为“ 花费时间做某事”。It 是形式主语，代替不定式短语。此句是将来时态。3.D 本题用的是 there be 句型。There is no need to是这个句型的一种表达方式，意思是“ 没有必要”。4.D I had expected 的宾语是前面所提到的 play。英语中，通常用 it 和 one 来替代前面单数名词，可以选 C 或 D， one 所代替的是同类事物中“一个” ，而 it 所代替的是前面提到过的同一事物，所以答案为 D。5.A to master a fore
44、ign language without much memory work 是动词不定式短语作 think 的宾语。当句子的宾语是动词不定式或 that 从句时，我们通常用 it 作形式宾语，但是如果宾语不与形容词在一起，一般不能用 it 作形式宾语。6.B 本题是一般疑问句。matter( 有关系，要紧) 经常用于否定句和疑问句，常用句型是：Does it matter? It doesnt matter。7.C 不定代词 one 常用来代替与前面已提到的一个事物（人或东西），以避免重复。one 表示同类事物中的“任一个”，即：表示泛指，而 the one 则表示确指。人称代词 it 被用来代替前面提到的那个东西。不定代词 each 常表示“每一个”的意思。根据题意（你要用我的尺子吗？不，谢谢。我自己有一支。）和结构，应选 C。8.A 不定代词 one 和 the one 都可以被用来代替前面提到过的一个同类事物（人或东西），以避免
