1、it作形式主语和形式宾语it作形式主语和形式宾语在句中作主语，表示“时间”、“距离”、“天气”等。它还能够引导强调句，使语气得以增强。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，而仅仅协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，能够代替三种形式： 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 + (for/of sb.) to do sth. It + be + 名词 + to do sth. It takes sb. some tim
2、e 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 these places as rubbish d
3、umps. 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 help those in need. 协
4、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，在逻辑上能够作sb.的表语，则sb.前应用介词of，否则就用for。 如： Its nec
5、essary 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. 感谢你对我的协助。（= 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
6、 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. 问他没有用。 （ it作形式主语,代替
7、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： 这个主语从句能够用连词that引导，也能够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 whether she will
8、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 be opened to traf
9、fic） 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 that he conti
10、nues 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/ surprising/
11、 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. 我们理应互相学习，互相协助，这是很重要的。 It was obvious that the child had be
12、en 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
13、如： It 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
14、 that the 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
15、事故中有二十多人丧生。 It is 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
16、 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 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
17、 not. 他来还是不来都没关系。 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，能够代替三种形式： 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 如： I find it pleasant t
18、o work with him. (it 作形式宾语，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。 She thinks it her duty to help us. （ it 作形式宾语，代替不定式短语to help us） 她觉得协助我们是她的责任。 I think
19、it my honor to be invited to speak here. （ 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，
20、代替不定式短语to go on with the work） 这些噪音使我无法继续工作。 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) 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 abso
21、lutely senseless attempting the impossible. 想做不可能的事情，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 s
22、ee 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 强调句型能够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，能够用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。例如我们能够用强调句型强调下列句子的主语（如 ）、宾语（如 ）、地点状语（如 ）即时间状语（如 ） I met Peter i
23、n Japan last year. It was I who/that met 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
24、 oclock that Mr Brown came back. 例2 The rain didnt 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 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 you
25、r dad worked two years ago? Its + 地点状语+ that （强调句） Its +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。 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.
26、(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 如： If it is convenient to you, you can start tomorrow. 如果方便的话，你明天能够动身。 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。
27、Believer it or not, we were left waiting in the rain for two hours. 信不信由你，我们冒雨一直等了两个小时。 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。 It is /has beensincedid(时间
28、状语从句) 如： It is just a week since we arrived here. 我们来这里已一星期了。 It wont be 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
29、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 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
30、什么事，他仅仅在装呢。 There is no doubt about对毫不怀疑 There is no doubt that对毫不怀疑 如： 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 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
