英语中it的用法及练习

【导语】标准的英语会对英语学习者产⽣积极的影响。

许多英语学习者都想要说⼀⼝地道的英语。

以下是由整理了关于解析英语句⼦语法，欢迎阅读!【篇⼀】关于解析英语句⼦语法 It 的⽤法 <例句> It was you who had been wrong. 错的是你。

<语法分析> it 强调句⼦的主语，可⽤ who 或 that 引导句⼦的后⾯部分。

⽤于强调的 it，可以对句⼦的某⼀处成分加以强调。

例如可以强调句⼦的主语、宾语以及状语等。

It 的⽤法有很多，它最基本的⽤法是作代词，主要代表刚提到的事物以避免重复，也可以代表某些抽象事物或代表⼀个彼此都知其何所指的东西。

有时也可以不指具体的东西，例如天⽓、环境和时间等。

先⾏词的it 主要作为句⼦的形式主语，从⽽使句⼦变得平稳。

<触类旁通> (1) It was a great surprise to me when she did a thing like that. 她做这样的事情我⼤为吃惊。

语法分析：It代表抽象的事物。

(2) Where does it hurt? 哪⼉疼? 语法分析：it代表⼀个彼此都知其何所指的东西。

(3) How fat is it to Beijing? 到北京有多远? 语法分析：it代表距离。

(4) It was she who lent us the money. 是她借钱给我们的。

语法分析：it⽤于强调句中，强调句⼦的主语。

(5) It's beyond me to say why. 我⽆法说个究竟。

语法分析：It作先⾏词，作句⼦的形式主语，有平稳句⼦的作⽤，句⼦谓语有这⼏种：be +形容词或名词，介词短语+不定式，及物动词+宾语+不定式。

<巩固练习> 1. _____ says here there was a big fire in the city. 2. “Why, ____ is you!” she cried. 3. _____ takes two to make a quarrel. 4. Why is _____ that everyone thinks I'm narrow-minded? 5. Was _____ you that broke the window? 6. Does _____ itch much? <参考答案>1. It2. it3. It4. it5. it6. it【篇⼆】关于解析英语句⼦语法 ⾃⾝代词和相互代词 <例句> She prided herself on her cooking. 她为⾃⼰的烹调技术感到骄傲。

it的特殊用法（单选题30题）中考英语专题练习一、单选题（共30题）1．It’s necessary for students ________ eye exercises.A．do B．doing C．to do2．_________ that the umbrella was invented four thousand years ago by Chinese people.A．It’s saying B．It’s said C．That’s said3．—We will do what we can ________ English well this term. —It’s time for you ________ hard. A．study; to work B．to study; work C．study; work D．to study; to work4．It’s important for us ________ to our teachers when we have problems.A．to talk B．talking C．talks D．talk5．— Who was calling you on the phone just now? — ________ was my mum.A．She B．That C．It D．This6．________ is necessary for us to wash hands when we are back home.A．It B．That C．This7．—What's the cost of the dictionary? —_________ is sixty-three.A．This B．It C．That D．He8．—Were you required___________ home during the outbreak of COVID-19?—Yes. Luckily, the Internet made it possible for many of us________ from home.A．to stay; to work B．staying; to work C．to stay; work D．staying; work9．W e find ________ more useful for students to do new eye exercises.A．it B．this C．one D．that10．W e decide to make________a rule for us to turn off the lights at 10:30 p. m.A．that B．this C．it D．one11．Laura, someone is ringing the doorbell. Go and see ________, please.A．who is he B．who it is C．who is it12．I t is very important for us ________ English well.A．learn B．learning C．to learn D．learned13．I found ________difficult for me to finish the work on time.A．that B．it C．this14．The 5G network will make it easier for us our life.A．enjoy B．to enjoy C．enjoyed D．enjoying15． is quite easy for people to find any place in the world with the help of online maps. A．That B．It C．One16．Chinese people find ____________ our duty to help develop African countries along the Belt and Road（“一带一路”）.A．it B．this C．that D．these17．---Is this iPad yours?---Yes. My parents bought _____ for my language learning.A．one B．it C．other D．another18．—Mario, your mobile phone is ringing.—Wait a minute. It’s dangerous for us it while crossing the street.A．answering B．to answer C．answer D．answered19．It’s time ________ class. I must go into the classroom.A．for B．of C．in D．after20．We all th ink ________ comfortable to live in Yancheng. It’s a beautiful and modern city. A．this B．that C．it D．what21．The chairman thought ________ necessary to invite Professor Johnson to speak at the meeting. A．that B．it C．this D．him22．I hate ________ if people say the matter of indifference in public.A．those B．it C．them23．I found ________ difficult to learn English grammar.A．it B．that C．it is D．that is24．—Jim finds ________ easy to remember all the English words.— ________ a smart boy he is!A．it; What B．that; How C．this; What D．it; How25．It is ________ to be able to speak a foreign language.A．helping B．help C．helpful D．to help26．Well done! It’s clever ________ you to work out the Maths problem.A．for B．of C．as D．in27．Chinese scientists sent up Tianwen I into space last July. It will take about 10 months ________ on the Mars.A．to land B．lending C．land D．landed28．We all think ________ necessary to stop school bullying (学校欺凌).A．it B．that C．this D．its29．It takes me about an hour ______ my homework on weekdays.A．finish B．finishes C．to finish D．finishing30．I found ________ difficult to talk to foreigners in English.A．that B．it C．this D．its【参考答案】一、单选题（共30题）1．C【详解】句意：学生做眼保健操是必要的。

高中英语语法高考二轮复习it考点讲义【精讲版】it用作形式主语和形式宾语的用法归纳总结一、用作形式主语当不定式、动名词、从句等用作主语时，避免头重脚轻，通常在句首使用形式主语厄而把真正的主语放在句子末尾。

如：It is stupid to do such a thing.做这种事真蠢。

It's no good sitting up too late.熬夜没有好处。

It is necessary that he should be sent there at once.有必要马上派他到那里去。

注：类似以下句子中的il也可视为形式主语：It happened that the harvest was bad in 1988.碰巧1988 年的收成很不好。

It seems that she is afraid to tell them about it.似乎她怕将此事告诉他们。

二、用作形式宾语当不定式、动名词、从句等用作宾语且其后跟有宾语补足语时，就应在宾语补足语前使用形式宾语，而将真正的宾语移至句末。

如：I've made it a rule never to hurry,我已养成凡事从容不迫的习惯。

Do you think it possible to root out crime?你认为可以根除犯罪吗？He found il difficult to breathe at high altitudes.他觉得在高空呼吸困难。

注：通常意义的形式宾语主要见于真正宾语为不定式、动名词、从句等且其后跟有宾语补足语时的情形，即用于“动词+it+宾语补足语+真正的宾语”这样的结构，但以下两类形式宾语却比较特殊，其后没有宾语补足语:1.由于介词后通常不能直接跟that从句作宾语，有个别特殊结构就在介词后先接it作形式宾语，再跟that从句。

如：You may depend on it that it is true.你可以相信这是真的。

It在强调句中的用法考点透视高中高三英语教研组It一词是高中英语中考查比较频繁的一个词，it含义简单却用法众多，透过近几年的高考试题我们可以看出，各省份高考试题对it的考查十分频繁，尤其是关于it在强调句中的用法的考查更是成为了考查的热点。

以下本文结合近几年高考试题对it在强调句中用法的考查，来对it在强调句中的用法进行一个详细的解析和回顾，通过对照高考真题，归纳讲解it在强调句中的用法，以方便同学们进一步系统牢固地掌握有关it在强调句中的种种用法：1．强调句型的基本结构是：“It is (was) +被强调部分+ that (who) + 其它”被强调部分如果是指人则引导词可以用who，其余情况都用that。

强调句也可以有变体形式，例如：It may have been at the Christmas that John gave Mary a handbag.It might have been John who gave Mary a handbag.强调句的判定方法是：将强调句中的it is/was以及连接词that或who去掉，如果句子仍然成立，成分仍然完整，则说明该句是强调句。

强调句理论上可以强调除谓语以外的任何成分，但是在正式英语中，强调句也一般不强调表语（或叫做主语补足语），例如：It is I who am to blame. （强调主语）It was a new pen that Mother gave me.（强调宾语）It was in the classroom that I left my umbrella.（强调地点状语）It is at eleven that the train leaves.（强调时间状语）It was just as he ordered that I acted.（强调方式状语）It was because he was in trouble that I tried my best to help him.（强调原因状语）It was chairman that they elected him.（强调宾语补足语）相关高考试题：（1）It was after he got what he had desired _______ he realized it was not so important.（06年高考辽宁卷第35题）A. thatB. whenC. sinceD. as（2）David said that it was because of his strong interest in literature _______ he chose the course.（06年高考上海春季招生卷第35题）A. thatB. whatC. whyD. how（3）It is what you do rather than what you say _______ matters.（05年高考天津卷第9题）A. thatB. whatC. whichD. this（4）It was only with the help of the local guide ________.（05年高考上海春季招生卷第37题）A. was the mountain climber rescuedB. that the mountain climber was rescuedC. when the mountain climber was rescuedD. then the mountain climber was rescued 答案：（1）A（2）A（3）A（4）B2．强调句的疑问句形式：强调句的一般疑问句：Is/Was it + 被强调部分 + that /who强调句型的特殊疑问句：疑问词 + is/was it + that/who（1）I just wonder ____ that makes him so excited.（06年高考山东卷第32题）A. why it doesB. what he doesC. how it isD. what it is（2）—____ that he managed to get the information?—Oh, a friend of his helped him.（05年高考山东卷第31题）A. Where was itB. What was itC. How was itD. Why was it答案：（1）D（2）C3．It is/was not until…that…表示“直到……时候才”，也是一个强调句型。

教师辅导讲义3.It is nearly half a century the first computer was invented.A. whenB. thatC. sinceD. until4.It_______ to accomplish the return journey.A. coast us 15 daysB. spent 15days for usC. was 15 daysD. took us 15 days5. ________ from Beijing to London!A. How long way it isB. What long way is itC. How long way is itD. What a long way it is6. ________ is reported in the newspaper, talks between the countries are making progress.A. ItB. AsC. ThatD. What7. ________ is known to all that China is rich in natural resources.A. ItB. ThatC. WhatD. As8. ________ quite a few techniques to learn language well.A. It seems to haveB. There seem to beC. There seems to haveD. It seems to be9.Someone is ringing the doorbell. Go and see .A. who is heB. who he isC. who is itD. who it is10. It was 7 o'clock he came here yesterday.A. thatB. whenC. beforeD. since11. _______ that I was watching TV when he came to see me.A. It happenedB. What happenedC. That happenedD. It was happened12.The chairman thought necessary to invite Professor Smith to speak at the meeting.A. thatB. itC. thisD. him13.The Foreign Minister said, "________ our hope that the two sides will work towards peace."A. This isB. There isC. That isD. It is14. _______ is reported in the newspaper that the terrible flood has caused a loss of 10 million yuan.A. ItB. ThisC. ThatD. As15.It's up to you whether we should go to the art exhibition right now.A. decidingB. to decideC. of decidingD. decide16.W as________ that I saw last night at the corner?A. it youB. not youC. youD. that yourself17.It is about two months James leaves school. He is going to be a lawyer.A. whenB. beforeC. sinceD. that18. _______ turn is ________ to clean the blackboard?A. Which... itB. Whose... itC. Which... thatD. Whose. .. that19.The seriously injured man has stopped breathing. will be no possibility of making him come to life.A. ItB. ThereC. ThatD. This20.Space exploration has been made with the development of modern science.A. it possibleB. it wasC. that being possibleD. possible21.To improve my spoken English, I make to recite a passage of English every day.A. a ruleB. it a ruleC. a rule thatD. a rule it is22.He moved to a new flat because is only five minutes' walk from the new flat to his office.A. itB. thisC. thatD. there23.It was________ s everal years I had an opportunity of seeing the bird again.A. for... beforeB. not for... thatC. for... whenD. not for... then。

1.it／one ／that三者均可用作代词指代前面提到的名词。

一般说来 it指代同名同物; one与that则指代同名异物。

I have lost my umbrella; I’m looking for it. （该句中it就是指前面的my umbrella）I have lost my umbrella; I think I must buy one. （one在该句中表泛指因为my umbrella已经丢了）The umbrella you bought is cheaper than that I bought. （替代词that在该句中特指“the umbrella I bought” 以区别“the umbrella you bought”）2.one与that虽可用来指代同名异物但one为泛指相当于a／an＋名词; that为特指相当于the ＋名词。

所以one所指代的名词的修饰语一般为 a／an ／some ／any; that所指代的名词的修饰语往往是the ／this ／that。

A chair made of steel is stronger than one made of wood. （该句中one可以换成a chair）The water in the cup is hotter than that in the pot. （该句中that可以换成 the water）3.one只能代替可数名词单数代替可数名词复数时用ones; that既可以代替不可数名词也可以代替可数名词单数代替可数名词复数时用 those。

I like this pen more than that one. （one代替可数名词单数pen）There were a few young people and some older ones in the house. （ones代替可数名词复数people）Mary’s handwriting is far better than that of Peter. （that代替不可数名词 handwriting）These pictures are more beautiful than those. （those代替可数名词复数 pictures）4.one既可代替事物也可代替人 that只能代替事物而不能代替人。

人教版高中英语选修六知识点梳理重点题型（常考知识点）巩固练习it的用法（1）概念引入小词it是我们学英语之初就学会的，是不是感觉它似乎有点无所不能，经常出现呀？那么我们是不是已经了解了it的用法了呢？本单元和下单元我们就把it的用法做一小结。

先看这些句子，想想it的用法是什么？1. It is a beautiful day here and I am sitting under the big tree at the end of the garden.(表天气)2. It seems amazing that at my age I am still fit enough to cycle 20 kilometres in anafternoon.(代替that从句作主语)3. It’s my birthday in two weeks’ time and I’ll be 82 years old!(表时间)4. Your mother tells me that you started smoking some time ago and now you are finding itdifficult to give it up.(第一个it代替to give it up作宾语；第二个it代替上文中“吸烟”的事) 下面我们就先学习it作为代词和形式主语、形式宾语的用法。

用法讲解代词it1. 作人称代词人称代词it是有实义的，是单数第三人称代词。

主格与宾格相同。

1）指代人以外的一切生物或事物，如前文提到的事物或未指明但谈话双方都知道的那件事；Ningbo is a beautiful city, isn’t it? 宁波是座美丽的城市，是不是？It doesn’t matter. 没关系。

2）替代前文中的this, that；This is your plan? Will you hand it in? 这是你的计划？你要交上去吗？3）指代婴儿、小孩或性别不明的人。

中考英语it的常考句型及知识点归纳（附练习题）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。

英语中it的用法系统练习（答案详解）一、it作代词(1)在答语中替代this或that。

如：---What's this？---It's a frog.(2)指已提到过的物体。

如：I've lost it on my way home.(3)指情形、行为等。

如：Jack is ill. Have you heard about it?(4)指人（不明的人或婴儿）。

如：Who is it?(5)指天气、温度、时间、距离等。

如：It is raining. It's very hot. It's five o'clock.二、引导词it(1)作形式主语。

如：1) It is difficult to understand the passage.2) It is no use trying.3) It is said that the meeting will be put off.4) It+take+(sb.) some time / some money+to do sth.例如:It will take them more than ten years to complete the Three Gorges Dam.5 )It+be+said / reported / told等+that-clause. 例如:It is said that he will leave for Beijing tomorrow.6) It+vt.+sb.+that-clause.例如:It worried her a bit that her hair was turning grey.[原题再现]①________is a fact that English is being accepted as an international language.A. ThereB. ThisC. ThatD. It②In fact________ is a hard job for the police to keep order in an important football match.A. thisB. thatC. thereD. it答案: ①D ②D（2）作形式宾语。

“ it ”的用法（强调句式、形式主语、形式宾语、代词）请指出下列句子中“ it ” 的用法：1.It is a tiny cleaner that you plug into (插入) your computer's USB port.2.It is strange that such non-traditional livestock should be raised on a long-established farm suchas ours, which has been in the family for generations.3.It's interesting and fun to experience other sports, not only for the benefit of relationships andfitness, but to cross train different muscle groups as you get older.4.It was thought that in order to make vowels, you had to have a low larynx (voice box), as humansdo.5.It is this ability to control the tongue, rather than the position of the larynx, that is key toproducing vowel like sounds.6.It’s really important to be a responsible tourist and to try to support the local economy.7.Music has certain obvious ways it can excite or relax us, but there are limits and it certainly can’treplace real treatments.8.Through these activities we teach students about the importance of civic engagement and wemake it fun for students to be involved in bettering their communities.9.Even if it's unclear exactly when it began, human language has developed greatly in the pastcentury, branching off into three different types: natural, artificial, and formal language.10.Conservation is the protection of things found in nature. It requires the sensible use of all Earth'snatural resources.11.Choose your classes from the schedule, complete the form, and return it by mail with your creditcard information.12.One of the things that we’ve learned is that it is the unexpected and natural behavior of the livingcreature that adds so much value to people’s experience.13.It became difficult for me to create new units and to market activities in my area after that, so Iwas asked to resign.14.It’s easy to understand why in Hawaiian folklore, people thought that the octopus was actuallythe last survivor of a lost universe.15.He added that it was important for teachers to shed the old ways of teaching and adapt themodern 21st century methods of working with learners.16.It doesn’t take special skills or even a huge amount of effort to help the environment. Small,simple things you can do every day can make a big difference.17.There is no denying these foods are tasty. But often, it’s the added salt that makes them soappealing.18.High blood pressure can make it difficult to be active.19.Bob McDaniel was looking for exactly those kinds of people because this lifelong resident ofSanta Ysabel, California, considered it his responsibility to save a barn (a large farm building for storing crops or keeping animals in).20.It is believed that the spirits of the dead visit their families on that day.21.As the nights draw in during the winter, many older people talk about how much more difficult itis to be on their own.22.It’s likely that people who are open to new experiences take those same attitudes toward food.23.Look for a taxi which has an orange light lit up over the driver’s window— this means that it isnot being used by anyone else.24.It had always been thought that nothing could escape a black hole.25.My goal is simple. It is complete understanding of the universe, why it is as it is and why it existsat all.26.It took a few seconds to reach each word and by the time he reached the end of a sentence, healmost forgot what the beginning of the sentence was about.27.Cynthia Marks is a single mother who finds it difficult to work all day and to put dinner on thetable every night for her four kids.28.They find it is beneficial just to be able to discuss a problem with another adult.29.The children are all in great spirits and it becomes impossible not to smile when these seriouslyill children seem so happy despite whatever condition they may have.30.According to new research, one contradictory feature of global warming is that it will probablylead to a period of much colder weather.31.There are a lot of myths (荒诞的说法) about how dangerous driving is — but the fact is that, it isriskier to be a walker or a jogger than to drive a car.32.While it’s t rue that women have more minor accidents than men, a man is twice as likely to bekilled in a car accident as a woman.33.Some wonder if it's better for people just to stay away from Antarctica if they are so likely toaffect the land negatively.34.Around 1300 the Venetian Glassmaker’s Guild made it illegal for cheap glasses to be made.35.Rob believes that with the right mindset it is possible to create far less waste and live a healthierlife.36.If we manage to clone the horse —it will be the first step to cloning the mammoth.37.It didn’t take long for the story to make its way to Google.38.It seems apparent to me that being kind to oneself certainly has selfishness involved.39.The teenager discovered that when oil is hit by UV rays from the sun, it reacts to form poisonouschemicals.40.It was astonishing seeing McCandless out in space by himself.参考答案：1.It is a tiny cleaner that you plug into (插入) your computer's USB port.（强调句式）2.It is strange that such non-traditional livestock should be raised on a long-established farm suchas ours, which has been in the family for generations.（形式主语）3.It's interesting and fun to experience other sports, not only for the benefit of relationships andfitness, but to cross train different muscle groups as you get older.（形式主语）4.It was thought that in order to make vowels, you had to have a low larynx (voice box), as humansdo.（形式主语）5.It is this ability to control the tongue, rather than the position of the larynx, that is key toproducing vowel like sounds. （强调句式）6.It’s really important to be a responsible tourist and to try to support the local economy.（形式主语）7.Music has certain obvious ways it can excite or relax us, but there are limits and it certainly ca n’treplace real treatments.（music）8.Through these activities we teach students about the importance of civic engagement and wemake it fun for students to be involved in bettering their communities.（形式宾语）9.Even if it's unclear exactly when it began, human language has developed greatly in the pastcentury, branching off into three different types: natural, artificial, and formal language.（形式主语）10.Conservation is the protection of things found in nature. It requires the sensible use of all Earth'snatural resources.（conservation）11.Choose your classes from the schedule, complete the form, and return it by mail with your creditcard information.（the form）12.One of the things that we’ve learned is that it is the unexpected and natural behavior of the livingcreature that adds so much value to people’s experience.（强调句式）13.It became difficult for me to create new units and to market activities in my area after that, so Iwas asked to resign.（形式主语）14.It’s easy to understand why in Hawaiian folklore, people thought that the o ctopus was actuallythe last survivor of a lost universe.（形式主语）15.He added that it was important for teachers to shed the old ways of teaching and adapt themodern 21st century methods of working with learners.（形式主语）16.It doesn’t take special skills or even a huge amount of effort to help the environment. Small,simple things you can do every day can make a big difference.（形式主语）17.There is no denying these foods are tasty. But often, it’s the added salt that makes them soappealing.（强调句式）18.High blood pressure can make it difficult to be active.（形式宾语）19.Bob McDaniel was looking for exactly those kinds of people because this lifelong resident ofSanta Ysabel, California, considered it his responsibility to save a barn (a large farm building for storing crops or keeping animals in).（形式宾语）20.It is believed that the spirits of the dead visit their families on that day.（形式主语）21.As the nights draw in during the winter, many older people talk about how much more difficult itis to be on their own.（形式主语）22.It’s likely that people who are open to new experiences take those same attitudes toward food.（形式主语）23.Look for a taxi which has an orange light lit up over the driver’s window— this means that it isnot being used by anyone else.（a taxi）24.It had always been thought that nothing could escape a black hole.（形式主语）25.My goal is simple. It（goal）is complete understanding of the universe, why it（the universe）is as it（the universe）is and why it（the universe）exists at all.26.It took a few seconds to reach each word and by the time he reached the end of a sentence, healmost forgot what the beginning of the sentence was about.（形式主语）27.Cynthia Marks is a single mother who finds it difficult to work all day and to put dinner on thetable every night for her four kids.（形式宾语）28.They find it is beneficial just to be able to discuss a problem with another adult.（形式主语）29.The children are all in great spirits and it becomes impossible not to smile when these seriouslyill children seem so happy despite whatever condition they may have.（形式主语）30.According to new research, one contradictory feature of global warming is that it will probablylead to a period of much colder weather.（global warming）31.There are a lot of myths (荒诞的说法) about how dangerous driving is — but the fact is that, it isriskier to be a walker or a jogger than to drive a car.（形式主语）32.While it’s t rue that women have more minor accidents than men, a man is twice as likely to bekilled in a car accident as a woman.（形式主语）33.Some wonder if it's better for people just to stay away from Antarctica if they are so likely toaffect the land negatively.（形式主语）34.Around 1300 the Venetian Glassmaker’s Guild made it illegal for cheap glasses to be made.（形式宾语）35.Rob believes that with the right mindset it is possible to create far less waste and live a healthierlife.（形式主语）36.If we manage to clone the horse —it will be the first step to cloning the mammoth.（形式主语）37.It didn’t take long for the story to make its way to Google.（形式主语）38.It seems apparent to me that being kind to oneself certainly has selfishness involved.（形式主语）39.The teenager discovered that when oil is hit by UV rays from the sun, it reacts to form poisonouschemicals.（oil）40.It was astonishing seeing McCandless out in space by himself.（形式主语）。