it的用法

it 的用法 一 人称代词 1,it 的最基本用法是作代词, 主要指刚提到的事物, 以避免重复 : 1They watched the train until it disappeared in the distance. 2., 也可以指动物或婴儿 ( 未知性别的婴儿或孩子 ): 2Is this your dog?no, it isn t. 3They got a baby and it was a ten-pounder 3., 也可指抽象事物或指抽象环境和情景 : 3I hate it when people talk with a full mouth.. 二. 非人称代词 1.it 有时并不指具体的东西而泛指天气 时间 日期 距离 价值 度量 温度 环境等 : ⑴. 指天气 :It is a lovely day, isn t it? ⑵. 指时间 : It was nearly midnight when she came back. ⑶. 指日期 :It is April First today. ⑷. 指距离 :It is some 3000 kilometers from A to B. ⑸. 指价值 :It is three dollars. ⑹. 指温度 :Today it is 30 degrees centigrade. 三 其他用法 1. 在句子的主语不太明确时充当主语, 表示谁在做某事 : 1Who is it there? It's I (me/you/he...). 2I thought it was Mary, but it was not she. 3Her face lighted when she saw who it was. 2. 泛泛的指某件事 : ( 有时泛指一般情况 ) 1It doesn t matter. 2It is a shame, isn t it? 3How is it going?( 情况怎样 ) 4It says in the newspaper that... 3.it 用在一些词组中,it 没有特别的意思 The last train's gone. Come on, we'll foot it.( 来, 咱们步行吧 ) 四 作形式主语, 替代主语从句, 动词不定式, 或动名词短语 : 1. 作形式主语替代主语从句 ⑴It is clear ( obvious, true, possible, certain...) that 从句常译为 " 清楚的 ( 显然的, 真的, 可能的, 肯定的...)" It is very clear that he s round and tall like a tree. = That he s round and tall like a tree is very clear. ⑵It is important ( necessary, right, strange, natural...) that 从句常译为 是重要的 ( 必要的, 对的, 奇怪的, 自然的 ).that 后的从句中要用虚拟语气 (should + 动词原形 ),should 可以省去, 建议记住该句型中的形容词 1It is important that we (should) learn English well.2it is necessary that he (should) remember these words. ⑶It is said (reported/ learned/believed/thought/known/told/hoped...) that 从句常译为 " 据说 ( 据报道, 据悉...)" 1It is said that he has come to Beijing. 2It is reported that another earth satellite has been put into orbit. ⑷It is suggested ( advised/ ordered / demanded/ insisted/ commanded... ) that 从句.that 后的从句要用虚拟语气 (should + 动词原形 ),should 可以省 ; 常译为 " 据建议 ; 有命令...) 1It is suggested that the meeting ( should ) be put off. 2It was ordered that we ( should ) arrive there in two hours. 1

⑸It is time ( about time,high time ) that 从句 ( 虚拟语气 : 动词用过去时 did) 1 It is time that children went to bed. ⑹It is the first ( second... ) time that 从句 ( 从句用现在完成时 have done ) It was ( 从句用过去完成时 had done ) 常译为 " 是第一 ( 二 )... 次..." It is the first time I have been here. = This is the first time I have been here ⑺It is a pity ( a shame /an honour/a good thing/a fact,/a surprise/... ) that 从句. that 后的从句一般用虚拟语气 (should + 动词原形 ),should 可省去. 表示出乎意料, 常译为 " 竟然 " 没有这种意义时, 则不用虚拟语气 1It 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! 2It is a pity that he is ill. 他生病了, 真遗憾! ⑻It happens (seems, looks, appears ) that 从句. 常译为 碰巧, 似乎是, 看起来 1It happened ( so happened ) that he met his teacher in the street. 碰巧... 2It seems that he will be back in a few days. 看来... 2. 作形式主语替代不定式. ⑴ It is kind ( of sb. ) to do sth. 不定式的逻辑主语是由 of 引起, 主句中的形容词必须是能表示逻辑主语特征的褒义或贬义形容词 常见的词有 : bad, brave, careless, clever, cruel, foolish, good ( 好心的 ), honest, horrible, kind, lazy, modest, naughty, nice( 有教养的 ), polite, rude, silly, stupid, wise, wrong( 错误的 ) 等 这个句型可以改写为 :sb. is kind to do sth. 如 :It is kind of you to say so. = You are kind to say so. ⑵It is necessary ( for sb. ) to do sth.. 不定式的逻辑主语是由 for 引起, 主句中的形容词通常是表示重要性, 紧迫性, 频繁程度, 难易, 安全等情况的中性形容词 常见的形容词有 : important, necessary, natural easy, safe, common, normal, hard, difficult, dangerous, unusual, rare, impossible, pleasant 如 :It is important for her to come to the party. = It is important that she (should ) come to the party. ⑶It takes sb.... to do sth. 常译为 " 做... 要花费某人..." 如 :It took thousands of people many years to build the Great Wall. 3. 作形式主语替代动名词短语 It is no good / no use / useless doing sth. 常译为 有好处或没有用 1It is no good learning English without speaking English. 2It's useless trying to argue with Shylock. 五 作形式宾语, 代替不定式, 动名词短语或宾语从句 We think it important to learn a foreign language. 该句型中的 it 作形式宾语, 该结构中常用的动词有 :think, believe, make,find consider, feel; 如 : We think it our duty to clean our classroom every day. He felt it important learning English well. They found it difficult that they would finish their work in two days. The Internet makes it easier for companies to keep in touch with customers. CF: keep sth, in mind / keep in mind that 2

六.it 的重要句型 1. 强调句型 : It is/was + 被强调部分 + that 从句 ( 被强调的主语如果是人,that 可以由 who 换用 ) 1It was about 600 years ago that the first clock with a face and an hour hand was made. 2It was they that (who ) cleaned the classroom yesterday. 特例 :It is not until + 被强调部分 + that... 该句型也是强调句型 主要用于强凋时间状语, 译成汉语 " 直到... 才...", 可以说是 not... until... 的强调形式 It was not until she took off her dark glasses that I realized she was a famous film star 主谓一致 谓语受主语支配, 须和主语在人称 数上保持一致, 叫主谓一致 处理主谓一致问题可依据三项原则 : 语法上一致 意义上一致和就近一致 一 语法上一致 : 谓语和主语通常是从语法形式上取得一致, 即主语为单数形式, 谓语动词也采用单数形式, 主语为复数, 谓语也为复数形式 A 谓语用单数的情况 1 以单数名词或代词 动词不定式 动名词短语或从句作主语时 例 :The boy is clever enough to study maths well. To work hard is necessary. Reading aloud is very important in learning a foreign language. Whether she comes or not is of no matter. 2 由 and 连接的并列单数主语的前边如果分别有 each, every, 或 no 修饰时, 其谓语要用单数形式 例 :In our country every boy and every girl has the right to education. No teacher and no student is going to take part in such a boring game. 3 主语是单数, 其后尽管有 as well as, no less than, rather than, more than, but, except, besides, with, along with, together wit h, like, including, in addition to 等起连接作用的词语带其他名词, 谓语动词仍用单数 例 :The teacher as well as the students likes this painting. 4 某些不定代词, 如 either, neither, each, one, the other, another, anybody, anyone, anything, somebody, someone, som ething, every body, every one, everything, nobody, no one, nothing. 等, 当它们作主语时, 通常用单数 5 many a + 单名, 谓语用单数 例 :Many a student is coming. 6 the number of+ 复数名词, 谓语用单数, 中心词是 number 二 意义一致 : 从意义着眼处理主谓一致问题, 即主语形式为单数, 意义为复数 谓语依意义而定用复数, 反之, 主语形式为复数, 意义为单数, 谓语用单数 7 表时间 距离 价格 度量等的复数名词或短语作为一个整体看时, 谓语动词用单数 例 :Fifty years is not a long time. One hundred kilometers is a good distance. Four hundred dollars is more than she can afford. 3

Five pounds is quite enough. 8 在说一个算式时, 表数目的主语通常作单数看, 谓语用单数 例 :20 plus 5 is 25. 9 以 ics 结尾的学科名称, 如 mathematics, physics, politics, news, works 等都属形复意单名词, 谓语用单数 例 :Mathematics seems to be difficult to me. The glass works was rebuilt in 1959. 10 用作书名 剧名 报纸名 国名等复数名词作主谓时, 谓语用单数 例 : The Arabian Nights is a very interesting story book. The United States is a capitalist country. B 谓语用复数的情况: 1. 主语为复数, 谓语用复数 例 :They are doing their homework now. 2. 用 and 或 both and 连接并列主语时, 谓语用复数 例 :Plastics and rubber never rot. He and I are classmates when we were at college. Both bread and butter were sold out in that shop. What he says and what he does do not agree. 但是 : 并列主语如果指的是同一人 同一事物或同一概念其谓语要用单数形式, 这时 and 后面的名词没有冠词 例 : In this hotel, the bread and butter (= the bread with butter on it) is served for breakfast. A cart and horse was seen in the distance. The girl s teacher and friend is a young doctor. Truth and honesty is the best policy. 3. 一些只有复数形式的名词如 clothes, scissors, trousers, shorts, scales, glasses 等, 它们作主语时, 谓语要用复数 例 :The scales are mine. My trousers are being washed. 但 : 如果成双的东西前有 a pair of 来修饰时, 谓语要用单数 例 :This pair of scissors belongs to the tailor. 4. 表总称意义的名词 public, police, cattle, people( 人们 人民 ) 作主语时, 谓语动词用复数 例 :The police have not made any arrests. People are talking about the news. 5. 以定冠词 the + adj( 或分词形式的 adj.) 作主语时, 如果指的是一类人, 谓语用复数 例 :The English speak English. The rich are not always happy. C 单复数依情况而定: 1 在主谓倒装句子中, 谓语动词的数应与其后的主语一致 例 :Here comes an old lady. 2 关系代词 who, that, which 等在定语从句中作主语, 其谓语动词的数应与句中先行词的数一致 例 :Those who want to go please sign their names here. Some of the energy that is used by man nowadays comes from the atom. 4

3 1 a lot of, lots of, plenty of, a heap of( 一堆 ), heaps of, a large quantity of 等 +n 构成的短语作主语 2 由分数 分数 +n 构成的短语作主语 3the rest of / the remainder of / most of/half of 短语作主语, 其谓语动词要根据短语中后面名词的数而定, 这是因为短语中后面的名词是中心词, 而短语中前面的量词是修饰语 例 :There are lots of people. Lots of damage was caused by the fire. Three-fourths of the people here are doctors Three-fourths of the surface of the earth is sea. Only 30 percent of the students are Only 30 percent of the water is The rest of the books are The rest of the water is Half of the visitors are from Europe. Half of the fruit is bad. Most of them are Most of the wood was used to make furniture. 4 有些集合名词, 如 family, team, group, crowd, crew, class, audience, government, company, committee 等作主语时, 如果看作一个整体用单数, 如果就其中的一个成员而言, 用复数 例 : family: My family is a big family. My family are watching TV. population: The population of the earth is increasing very fast. What is the population of China? One third of the population here are workers. 5 疑问代词 who, what, which, 不定代词 all, some, any, none 等, 谓语动词须视情况分别采取复数或单数形式 例 :Who is your brother? Who are league members? 三 就近一致有时谓语动词的人称和数与最近的主语保持一致 1 在正式文体中, 用连词 or, either or, neither nor, whether or, not only but also 等连接并列主语, 如果一个是单数, 一个是复数, 则谓语动词按就近一致原则, 与最靠近它的主语一致 例 :What he does or what he says does not concern me. Either he or I know the truth. He didn t say whether some English novels or an English dictionary was wanted. Not only he but also you are wrong. 2 在倒装句中, 谓语动词往往和后面的第一个主语取得一致 例 :Where is your mother and younger sisters? There is a notebook, a pen and some books on the desk. In the distance was heard the applause of the people, the shouts and clapping of hands. 但 : 也可按语法一致原则处理倒装句中主谓一致的问题 5

例 :There are a notebook, a pen and some books on the desk 省略 省略有词法上的省略, 也有句法上的省略, 某些替代也看作一种省略 一 词法上的省略 1. 名词所有格后修饰的名词在以下情况可以省略 1) 如果名词所有格修饰的名词在前文已出现, 则可以省略 如 : These are John's books and those are Mary's (books). 这些是约翰的书, 那些是玛丽的书 2) 名词所有格后修饰的名词如果是指商店 住宅等地点时, 这些名词也常常省略 如 : at the doctor's 在诊所 at Mr. Green's 在格林先生家 to my uncle's 到我叔叔家 at the barber's 在理发店 2. 冠词的省略 1) 为了避免重复 The lightning flashed and thunder crashed. 电闪雷鸣 (thunder 前省略了定冠词 the) 2) 在 the next day (morning, week, year...) 等短语中, 有时为了使语气紧凑定冠词 the 常可以省略 如 :We went to the farm to help the farmers with the harvest (the) next day. 第二天, 我们去农场帮助农民收庄稼 3) 在副词的最高级前面的定冠词常可以省略 如 : She sings best in the class. 她在班上唱歌唱得最好 4) 在某些独立主格结构中 如 : Our teacher came in, book in hand. (=Our teacher came in, with a book in his hand.) 我们的老师手里拿着一本书进来了 5) 在 as 引导的让步状语从句中, 当作表语的单数名词提前时, 不定冠词要省略 如 : Child as he is, he knows a lot. 虽然他还是一个孩子, 却懂得很多 3. 介词的省略 1)both 后常跟 of 短语, 其后可以接名词复数形式, 也可以接代词宾格复数形式 接复数名词时, 介词 of 可以省略, 但接代词宾格时,of 不能省略 如 : Both (of) the films were interesting. 这两部电影都很有趣 She invited both of us to her birthday party. 她邀请我们俩去参加她的生日派对 2) 在现在完成时表持续和重复的句型中, 一段时间前的介词 for 可以省略 如 :These shoes are worn out. They have lasted (for) a long time. 这双鞋穿破了, 已经穿了很长一段时间了 3) 被动结构中, 如果没有必要强调动作的执行者, 则可以省略介词 by 短语 如 : The letter was posted (by me) yesterday. 这封信是昨天寄出去的 4 ) 和一些动词搭配构成的短语中的介词, 如 : consider... (as)..., prevent / stop... (from)doing..., have trouble / difficulty... (in) doing...,spend... (in / on) doing... 等中的介词可以省略 如 : Trees can prevent the earth (from) being washed away. 树能阻止泥土被冲走 Can you stop him (from) going swimming in the river? 你能阻止他下河洗澡吗? I have some difficulty (in) answering the question. 回答这个问题我有点困难 4. 动词不定式中的省略 1) 有些动词, 如 :believe, find, think, feel, consider, imagine, prove 等后作宾补的结构 6

to be + n. / adj. 中的 to be 可以省略 如 : I consider him (to be) lazy. 我认为他懒 His mother found him (to be) a clever boy. 他母亲发觉他是一个很聪明的孩子 2) 感官动词 see, hear, feel, watch, notice 等以及使役动词 let, make, have 后作宾补的动词不定式中的不定式符号 to 要省略, 但变为被动结构时,to 必须保留 如 : They made the boy go to bed early. 他们强迫这个男孩早睡 The boy was made to go to bed early. 这个男孩被迫早睡 注 :help 后作宾补的动词不定式中的 to 可以省略也可以保留 3) 在 can not but, can not choose but, can not help but 之后的动词不定式一般不带 to; but 之前有实义动词 do 的某个形式 do, does, did, done 时, 也不带 to, 否则要带 to 如 : We have nothing to do now but wait. 我们现在除了等没有别的事可做 I can not but admire his courage. 我不能不钦佩他的勇敢 He has no choice but to accept the fact. 除了接受这个事实他别无选择 4) 在并列结构中为了避免重复 如 : I'm really puzzled what to think or say. 我真不知道该怎么想, 怎么说才好 但两个不定式有对照或对比的意义时, 则后一个 to 不能省略 如 : I came not to scold but to praise you. 我来不是责备你, 而是赞美你 5) 在 why, why not 引导的特殊问句中后跟省略 to 的动词不定式 如 : Why talk so much about it? 为什么大谈这个事呢? Why not try it again? 为什么不再试一试呢? 6) 动词不定式中动词原形部分是否省略, 主要看句子前面是否已出现过同样的动词 如果句子前面出现过同样的动词, 为了避免重复, 句子后面的不定式常省略动词原形, 而保留不定式符号 to 如 :They may go if they wish to(go). 如果他们想去, 他们就可以去 Don't go till I tell you to. 直到我告诉你去, 你才可以去 在一些动词 afford, agree, expect, forget, mean, pretend, remember, want, refuse, hope, wish, would like (love), try 等后跟动词不定式作宾语, 不定式中的 to 可以承前 ( 后 ) 省略 如 : -Will you go to the cinema with me? 你愿和我一起去看电影吗? -Well, I'd like to (go with you). 我愿意 I would do it for you, but I don't know how to (do it for you). 我想为你做这事, 但我又不知如何做 在某些形容词, 如 :afraid, glad, willing, happy, eager 等后承前省略动词原形, 只保留不定式符号 to 如 :-Will you join us in the game? 你愿和我们一起做这个游戏吗? -Sure, I'll be glad to(join you in the game). 当然, 我愿意 有些动词, 如 :tell, ask, allow, expect, force, invite, permit, persuade, order, warn, wish, would like, forbid 等后跟动词不定式作宾语补足语 主语补足语时, 不定式承前省略动词原形, 保留动词不定式符号 to 如: He didn't come, though we had invited him to (come). 尽管我们邀请他来, 他却没来 注 : 承前省略的动词不定式如果有助动词 have 或 be, 则要保留 be 或 have 如: -Are you a teacher? 你是老师吗? -No, but I used to be (a teacher). 不, 我以前是 二 句法中的省略 7

在一些简单句 并列句和复合句中, 可以省略主语 谓语 宾语 表语等某一个句子成分, 也可以省略多个句子成分 1. 简单句中的省略 1) 感叹句中常省略主语和谓语 如 : What a hot day (it is)! 多热的天啊! How wonderful! 多妙啊! 2) 在一些口语中可以省略某些句子成分 如 : -(Will you) Have a smoke? 你抽烟吗? -No. Thanks. 不, 谢谢了 (Is there)anything else to say? 还有别的要说吗? 2. 并列句中的省略 1) 如果主语不同, 而谓语动词中的一部分相同, 则省略谓语动词中相同的那部分 如 : John must have been playing football and Mary (must have been) doing her homework. 约翰一定在踢球, 而玛丽一定在做作业 2) 主语相同, 谓语动词也相同, 则二者都可以省略 如 : His suggestions made John happy, but (his suggestions made) Mary angry. 他的建议使约翰高兴, 却使玛丽很生气 3) 主语相同, 而谓语不同, 则可以省略主语 如 : Old McDonald gave up smoking for a while, but (he) soon returned to his old ways. 老麦克唐纳戒了一阵子烟, 可很快又抽上了 4) 在并列复合句中, 如果 that 从句从属于第二个并列句且它的谓语动词和宾语等其它一些成分与第一个并列句相同时, 这个 that 从句通常可以省略这些相同的部分 如 : Jack will sing at the party, but I know John won't (sing at the party). 杰克将在晚会上唱歌, 但我知道约翰不会在晚会上唱歌 3. 复合句中的省略 1) 名词性从句中的省略 (1) 作宾语的 what 从句中的谓语动词与主句的相同, 则 what 从句可以省略谓语, 甚至主语 如 :Someone has used my bike, but I don't know who (has used it). 有人用了我的自行车, 但我不知道是谁 He has gone, but no one knows where (he has gone). 他走了, 但没人知道他去哪儿了 (2) 有时候也可以根据说话的情景来省略主句中的一些成分 如 : (I'm) Sorry I've kept you waiting so long. 对不起, 让你久等了 (3) 在某些表虚拟语气的主语从句 宾语从句 表语从句和同位语从句中, 从句谓语动词中的助动词 should 可以省略 如 :It's important that we (should) speak to the old politely. 我们对老人说话要有礼貌, 这很重要 2) 定语从句中的省略 (1) 在限制性定语从句中, 作宾语的关系代词 that, which, who (whom) 常可以省略 如 : The man(who / whom) I saw is called Smith. 我见到的那个人名叫史密斯 Where is the book (which) I bought this morning? 今天上午我买的那本书在哪儿? (2) 关系副词 when, where, why 以及 that 在 the time(day, morning, afternoon, evening, night, week, month, 8

year 等 ) when, the place(desk, table, room, spot, house, town, country, school 等 )where, the reason why, the way that 结构中引导限制性定语从句时, 在非正式场合下, 可以省略关系副词 when, where, why, that 如: I shall never forget the day (when) we first met. 我永远也不会忘记我们第一次见面的那一天 The reason (why) he came so early is his own affair. 他来这么早是他自己的事 The way (that) you answered the questions was admirable. 你回答这些问题的方式令人钦佩 3) 状语从句中的省略当状语从句中的主语和主句的主语一致, 或状语从句中的主语是 it, 并且又含有 be 动词时, 常可以省略从句中的主语和 be 动词 (1) 在 as, before, till, once, when, while 等引导的时间状语从句中 如 : While(I was) waiting, I was reading some magazines. 我一边看杂志, 一边等 (2) 在 though, although, 等引导的让步状语从句中 如 : Though (they were) tired, they went on working. 虽然他们累了, 但他们仍继续工作 (3) 在 if, unless(=if... not) 等引导的条件状语从句中 如 : You shouldn't come to his party unless (you were) invited. 除非你被邀请, 否则你不应该来参加他的宴会 (4) 在 as, as if, as though 引导的让步状语从句中 如 : He did as (he had been) told. 他按照被告知的那样去做了 He paused as if (he was) expecting her to speak. 他停下来, 好像是在期待她说话 (5) 在 as(so)... as..., than 引导的比较状语从句中 如 : I know you can do better than he (can do). 我知道你能比他做得更好 This car doesn't run as fast as that one (does). 这辆小车不及那辆跑得快 三 替代性省略在一些交际用语中的某些动词, 如 :think, suppose, expect, believe,guess 等后常常和 so, not 等连用, 以替代上文出现的内容 如 : -Do you suppose he is going to attend the meeting? 你认为他会来参加这个会议吗? -I suppose not. 我认为不会 9