1、It作形式主语常见句型动词不定式，动名词或主语从句作主语时，通常把它们放在谓语动词前，而用it作形式主语，放到句首，常见句型有：1. It + be + 形容词+主语从句，如：It is uncertain whether he can come to Jennys birthday party or not.2. It + be + 名词词组 + 主语从句，这类名词有：a fact, a pity, a shame, an honour，a question等，如：Its a pity that you missed the exciting football match.It remain
2、s a question whether he will come or not. 3. It + be + 过去分词 + 主语从句，这类过去分词有：announced, believed, expected, hoped, decided, reported, said, shown等， 如：It is reported that 16 people were killed in the earthquake.It is not decided who will give the operation to the patient.4. It + 不及物动词(seem, appear, hap
3、pen等) + 主语从句, 这类不及物动词有：appear, happen, seem等， 如：It seemed that he didnt tell the truth.It happened that I was out when he called.5. It + be + 形容词 + for sb.）+ 动词不定式这类句型常用形容词easy, difficult, hard, important, possible，wise等作表语，有时候为了强调不定式动作的执行者，常在不定式前加for sb，如：Its necessary for the young to master two f
4、oreign language.It is unwise to give the children whatever they want.这类形容词有：easy, difficult, hard, important, possible，wise 6. It + be + 形容词 + of sb. + 动词不定式，这类形容词常是表示心理品质,性格特征的形容词，如：kind, nice stupid, clever, foolish, polite, impolite, silly, selfish, considerate等。某人和这些形容词可以构成主系表结构。如：Its very kind
5、of you to help me with the work.=You are kind to help me.It seemed selfish of him not to share his dictionary with others.=He seemed selfish not to share his dictionary with others.7. It + be +名词词组 + 动词不定式，如：It is not a good habit to stay up too late.8. It + be + 名词或形容词 + 动名词，这类名词和形容词常常是：good, no go
6、od, no use, a waste of, useless, senseless等，如：Its a waste of time talking to her any more.It is no use arguing about the matter with him.9. It + take ( sb. )+ 时间（金钱）+ 动词不定式，如：It took the workers almost three years to finish building the dam.It will take a whole day to get to the top of the mountain
7、on foot.实战演练：1. It is generally considered unwise to give a child he or she wants. (NMET 1997)A. however B. whatever C. whichever D. whenever2. In fact is a hard job for the police to keep order in an important football match. (2001 上海)A. this B. that C. there D. it3. is a fact that English is being
8、 accepted as an international language. (NMET1995)A. There B. This C. That D. It 4. Is necessary to take off our shoes when we enter the lab? (MET88) A. everyone B. this C. her D. it5. _ will take you a lot of time to find him in the crowd. A. It B. I C. We D. They6. It is no use his _ there, the si
9、tuation is hopeless now. A. to go B. to be going C. going D. having gone7. It is never too late to learn, _? A. is it B. isnt it C. does it D. doesnt it8. _ is known to all that Shenzhou VI Launched Successfully. A. As B. What C. It D. That 9. _ is reported in the newspaper, the Earthquake in east C
10、hinas Jiangxi Province killed 13 people A. It B. As C. That D. What10. _ certain that his invention will make peoples life convenient. A. Thats B. This is C. Its D. Whats11. _ that there is another football match on the air this evening. A. It says B. It was said C. It is said D. What was said12. _
11、that their daughter got an opportunity to study abroad. A. Its a exciting news B. This is an exciting news C. This is exiting news D. Its exciting news参考答案：15 BDDDA 610CACAC 1112CD 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。 it代替不定式短语常用于下列句型中：It + be +形容词 + (
12、for/of sb.) to do sth.It + be + 名词 + to 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
13、 Chinese）It is not right to use these 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 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s
14、b.的品质、品格，在逻辑上可以作sb.的表语，则sb.前应用介词of，否则就用for。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 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 foolish to give up the job it代替动名词短语
15、：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.问他没有用。（ it作形式主语,代替动名词短语asking him） it代替主语从句
16、：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。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 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
17、作形式主语,代替主语从句what she meant）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 thatIt was a pity that the engineer couldnt come.可惜工程师没能够来。It is a wonder that he continues to gamble when he always loses!令人惊讶的是他一直输还一直赌。 It is + 形容词（如： strange/ natural/
18、 surprising/ obvious/ true/ fortunate/ wonderful/ funny/ possible/ impossible/ likely/ unlikely/ clear/ unusual/ certain/ important）that It is certain that he will win. 他一定会取胜。 It seems/ happened/ turned out/ suddenly struck me/ occurred to methat It happened that I wasnt there that day. 恰好那天我不在那里。
19、It + be + 过去分词（如：said/ reported/ announced/ decided/ expected/ hoped/ known/ believed）thatIt 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。* 注意要在It is suggested/required/desired/ordered/pro
20、posedthat的主语从句中用虚拟语气： (should) + 动词原形It is requested that he give a performance at the party.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 doesnt matter +连接代词或副词It doesnt make too much difference +连接代词或副词It doesnt matter whether he comes or not.他来还是不来都
21、没关系。It wont make 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。 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I find it pleasant to work with him.(it 作形式
22、宾语，代替不定式短语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。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
23、续工作。 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)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。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.想做不可能的事情，他认为是完全没道理的。 it代替宾语从句：We all thought it a pity that
24、 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。 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。 It be + 被强调部分 + that/ who + 其他成分I met Peter in Japan last year. It was I who/that met
25、 Peter in 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Mr Brown didnt come back until eleven oclock.可变为：It was not until eleven oclock thatMr Brown came back.* 强调句也可变为特殊疑问
26、句例It was in 1949 that the PRC was founded.可变为：When was it that the PRC was founded? Its + 地点状语+ that（强调句） Its +地点名词+ where (定语从句)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。 Its + 时间名词+ when(时间状语从句) Its + 时间状语 +that
27、(强调句)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 returned.(8 oclock 是时间名词，时间状语从句)他回来的时候是八点钟。 if it is convenient to you 如果你方便的话If it is convenient to you, you can start tomorrow.如果方便的话，你明天可以动身。 believe it or not 信不信由你Believe it or not, Ill go abroad ne
28、xt month.不管你信还是不信，我下个月要出国。 Its time thatdid / should do (定语从句)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。 It is /has beensincedid(时间状语从句)It is just a week since we arrived here.我们来这里已一星期了。It wont be b
29、efore用不了（多长时间）就会It wasnt before没过（多长时间）就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。 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.There is nothing wrong /the
30、 matter with him. Hes just pretending.他没什么事，他只是在装呢。 There is no doubt about对毫不怀疑 There is no doubt that对毫不怀疑There is no doubt about his suitability for the job毫无疑问，他适合这个工作。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There was no need for him to
31、remain in Paris.他没有必要继续留在巴黎。 There is no/a possibility that 没可能/有可能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。 There is a chance that 可能There is a chance that the sick child will get well.这个生病的孩子可能会好起来的。 There be no/ s
32、ome differences betweenand和之间没/有区别There are some differences between the two languages.这两种语言之间有些区别。 After what seemed + 时间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。 There be difficulty/ trouble (in) doing sth. 干有困难There was no difficulty in
33、 finding him.找到他没费什么事。三. 形式主语、形式宾语专项练习1. Its easier _ than _. A. say, do B. to say, to doC. says, does D. saying, doing2. It takes me 30 minutes _ to school by bike every day. A. going B. to go C. goes D. go3. Its not easy _ us _ a foreign language. A. for; learning B. of; learning C. of; to learn D
34、. for; to learn4. Children find_ interesting to play computer games. A. that B. which C. it D. its5. Do you think it important _ computer well? A. play B. plays C. to play D. playing6. Is _ necessary to complete the design before National Day? A. this B. that C. it D. he7. I dont think _ possible to
35、 master a foreign language without much memory work. A. this B. that C. its D. it8. Does _ matter if he cant finish the job on time? A. this B. that C. he D. it9. Toms mother kept telling him that he should work harder, but _ didnt help. A. he B. which C. she D. it 10. _ is a fact that English is be
36、ing accepted as an international language. A. There B. This C. That D. It11. I hate _ when people talk with their mouths full. A. it B. that C. these D. them12. I like _ in the autumn when the weather is clear and bright. A. this B. that C. it D. one 13. _ happened _ he is unfit for the office. A. T
37、his; that B. That; that C. It; that D. He; that14. We took _ for granted that they would accept our advice. A. that B. this C. it D. them15. _ that the scientist will give us a talk next month? A. Is true B. Is it true C. Its true D. Its truly16. _ doesnt matter much _ dress you are going to wear. A
38、. This; that B. That; who C. It; which D. It; who17. _ is going to America for further study. A. He is said that B. People said that he C. It was said he D. It is said that he 18. They are good friends. _ is no wonder that they know each other so well. A. This B. That C. There D. It19. Is _ possible
39、 to fly to the moon in a spaceship? A. this B. there C. that D. it20. She liked _ when he kissed her. A. him B. that C. one D. it21. _ will do you good to do some exercise every morning. A. It B. There C. Those D. One22. We think _ our duty to pay taxes to our government. A. that B. this C. its D. i
40、t 23. Id appreciate _ if you would like to teach me how to use the computer. A. that B. it C. this D. you24 . -What do you think made Mary so upset? -_ her new bicycle.A. As she lostB. Lost C. Losing D. Because of losing25. Our monitor suggested 25_a discussion of this subject. A. to have B. should
41、have C. have D. having 26. Its very kind _ you _ me. A. for, helping B. of ,help C. for, to help D. of, to help 27 What do you think of the book？ -Oh, excellentIts worth _a second time. A. to readB. to be readC. readingD. being read28. Its no use forward to from her soon. A. to look; to hearB. looki
42、ng; hearingC. looking; hear D. look; hear29. It took the workmen only two hours to finish _ my car. A. repairing B. repair C. to repair D. repaired30. _ clean is a safeguard against disease. A. To be keeping B. Kept C. Keep D. Keeping参考答案15 BBDCC 610 CDDDD 1115 ACCCB1620 CDDDD 2125 ADBCD 2630 DCBADI
43、t”作形式主语和宾语It作形式主语和形式宾语用法，是中学阶段英语学习的主要语法项目之一。纵观历届高考题，无论是单项选择，还是完行填空，it用法始终是反复考查的重、热点之一。现将it在特殊句型中作形式主语和形式宾语用法，进行如下归纳分析，以供学习参考。一、 It 用作形式主语当不定式（短语）、动名词（短语）或从句在某个句子中作主语时，为保持句子结构前后平衡，避免头重脚轻，因此常用it作形式主语置于句首，而将真正的主语放在句尾。此时it只起先行引导作用，本身无词义。e.g. It is wrong to tell a lie. (说谎是错误的。) It为to tell a lie的形式主语It is no use arguing about it. (争吵是没用的。) It为arguing about it的形式主语It is unce
