it的用法 (2).ppt

it 的用法一、考查一、考查 it 用作形式主语的用法用作形式主语的用法当不定式、动名词、从句等用作主语时，为避免头重脚轻，通常在句首使用形式主语it，而把真正的主语放在句子末尾。如：Its no good sitting up too late. 熬夜没有好处。It is quite clear that he has read the book. 很显然，他读过这本书。It doesnt matter what he says. 他说什么没关系。【特别提醒】注意it用作形式主语的三类特殊句式：1.用作动词look, seem, appear, happen, occur, follow等的主语(后接that从句或as if从句)。如：It seems that he knows everything. 他好像什么都知道。It (so) happened that I had no money with me.碰巧我没带钱。It occurred to me that he helped me a lot.2.当系表结构后接有if 或when引出的状语从句时，通常在系表结构前使用形式主语表示说话人对某情况的看法。如： It was a great surprise to me when he did a thing like that. 他这样做使我很吃惊。It would be a tragedy if anything went wrong. 如果出了什么事就是一个悲剧。3.用于if it were not for / if it hadnt been for(若不是因为)。But for如：If it hadnt been for the freezing wind they could have reached the injured man in time. 要不是有刺骨的寒风，他们就及时赶到伤员身边了。二、考查二、考查 it 用作形式宾语的用法用作形式宾语的用法当不定式、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： We found it difficult to persuade her. 我们发现很难说服她。He makes it a rule to get up before dawn. 他习惯于天亮前起床。I think it very strange that he goes out walking almost every night. 我认为他几乎每晚都出去散步是很奇怪的。【特别提醒】注意it用作形式宾语的三类特殊句式：1. 动词+it+if / when从句当enjoy, like, dislike, love, hate, prefer, appreciate等动词后需要接一个if或when引导的从句时，此时必须要先在动词后接it作形式宾语。如：She wont like it if you arrive late. 她不喜欢你迟到。He hates it when people use his bike. 他讨厌别人用他的自行车。Id prefer it if I didnt have to do so much work. 要是我不必做那么多工作，那就太好了。I would appreciate it very much if you would help me with it. 如果你能帮助我做这事，我会十分感激。2. 动词+介词+it+that从句动词短语allow for（担保）、count on（期待）depend on（依靠）、insist on（坚持）、 see to（确保） ,answer for等后接that引导的宾语从句时，必须冠以形式宾语it。 。You may depend on it that he will turn up in time. 你可以相信他会及时赶到的。I cant answer for it that the boy is honest. 我不能保证这个男孩是诚实的。Ill see to it that all these letters will be sent to the post before twelve. 我将注意让所有的信件在12点以前送到邮局。3、动词have（表明，坚持说）、take（认为，猜想）、hide（隐藏）、publish（公布）、put（表达，写出来）等后接由that引导的宾语从句时，往往在从句的前面加上形式宾语。I take it that you will be leaving Shanghai soon.我认为你不久就离开上海。We published it that we had finished the project ahead of time. 我宣布我们已经提前完成了这项工程。 三、考查三、考查 it 在强调句中的用法在强调句中的用法强调句的基本结构是：It+be+被强调部分+that(who)+其他部分。It was yesterday that he got married. 他是昨天结婚的。It was a computer that he bought last week. 他上个星期买的是一台电脑。【特别提醒】对于强调句的复习要特别注意两种情形：1.当强调句有插入语或复杂修饰语时：It was lack of money, not of effort, that defeated their plan. 他们的计划受挫，原因是缺少钱而不是没有尽力。It was more in sorrow than in anger that he criticized his former colleague. 他批评以前的同事，并非出于气愤而是为他惋惜。2.当强调为特殊疑问句时：Who was it that won the World Cup in 1982? 谁赢得了1982年的世界杯? How long ago is it that you last saw her? 你上一次看见她是多久以前的事？四、考查四、考查 it 与与 one 的区别的区别两者均可代替前面提到的事物，区别是：it指的是与前面已提到的事物为同一物，此时的it等于“the (this, that, my.)+名词”；one 指的是与前面已提到的事物为同一类物，此时的one等于“a+名词”。比较：I have a dictionary but Ive lent it to Mary. 我有一本词典，但把它借给玛丽了。I havent a dictionary; can you lend me one? 我没有词典，你能借我一本吗?五、考查五、考查 it 在习语中的用法在习语中的用法包括it的习语很多，比如make it就是其中很重要的一例。如：You can make it if you hurry. 如果你赶快还可以及时赶到。He wants to make it as a writer. 他想作一名作家而一举成名。You neednt worry; he will make it. 你不必担心，他会办成的。It all depends=that depends 视情况而定if it is convenient to you 如果你方面的话believe it or not 信不信由你take it easy 别着急，慢慢来，别紧张， as it is 但是实际上，其实see (to it ) that 设法使，务必做到 if it had not been for 若不是=but forit was not long before 不久就cab it 乘车 brave it out 拼命干到底walk it 步行 do/go it alone单枪匹马的干beat it =go away 滚make it =succeed in doing 办成功 六 Its + adj + for/of somebody to do sth选择of 还是for，要根据形容词来决定， 如果表示人的内在品质，后面引出的名词既是前面形容词的主语，也是动词不定式的逻辑主语，那么用of, 这类形容词有kind, brave, merciful, fine, cruel, selfish, stupid, clever, wise, unfair等； 如果表示难易程度，可能性，等外在的特征，而且所引出的词只作后面动词不定式的主语，用for这类形容词有easy, difficult, hard, impossible, possible, convenient 等等。比如： It is easy for you to make it.It is impossible for him to walk 30 miles within one minute.It is very kind of you to help me.It is wise of you to take his advice.七 .it 引起的容易混淆的时间句型1、 it is/has been +段时间+since-clause 这个句型表示从since谓语动作发生以后到现在或过去所经过的一段时间，意思为：“自从以来已经多久了”，要注意：since引导时间状语从句时，从句若使用终止性动词，则表示该时间是从现在算起的 若使用延续性动词，则表示时间是从过去算起的。Its five years since they got married. 他们结婚已经五年了。（从现在算起）Its five years since they were married. 他们离婚已经五年了。（从过去算起） since从句中常用一般过去时，若从句中是持续性动词的一般过去时， 则表示该动作结束有多长时间了。如： It is three years since he smoked. 他不吸烟已有3年了。 试比较： It is three years since he began to smoke. 他吸烟已有3年了。 注意：在这种结构中， since引导的从句绝对不能用否定式的谓语动词来表示否定意义， 试比较： 他好久没学汉语了。 误：It is a long time since be didnt study Chinese. 正：Its a long time since he studied Chinese. (studied为持续性动词， 应从其动作结束时算起) since从句:1.如果谓语动词是延续性动词或是表示状态的动词, 时间应该从动作结束时算起; 如:Its 2 years since I smoked. 我戒烟已经两年了. (抽烟的这个动作是延续性的) 2.如果谓语动词是非延续性动词,时间要从动作开始时算起 如:Its 2 years since I left school. 我离开学校已经两年了. (离开的这个动作是短暂的) since后如果接短暂性动词，表示肯定的意思； 如果接延续性动词, 表示否定的意味。It is two months since he was ill.他病好已经两个月了。It is two months since he fell ill.他病了已经两个月了。2、It be +段时间+before-clause -这个句型中的时间是段时间（long years, months, weeks, days, hours, minutes）,主句中的谓语动词用肯定式，“过多长时才”。主句谓语动词是否定式时，“没过多长时就”。It was not long before she learned those poems by heart.她没过多久就会背那些诗了。It was long before the police arrived.过多长时才就It will be hours before he makes a decision.It will not be hours before we meet again.3、 It be +点时间+when-clause这个句型中，it指时间，而且表示时间的词语前没有介词，时间为具体时间。主句中的谓语部分和从句中的谓语动词在时态上一般是一致的，主句是will be时，从句中用一般现在时替换将来时。如：It was already 8 oclock when we got there.It will be late afternoon when they get there.It be +介词+时间+that-clause 此句型为强调句型4.It/This/That be the first(second/third) time that-clause这个句型表示说话时为止某人的一种经历，关键是time前面的序数词，主句是is时， 从句要用现在完成时，主句是一般过去时，从句要用过去完成时。This is the first time (that) these Europeans have visited the Great Wall.It was the fifth time (that) I had paid a friendly visit to America. 下面的句型中用there而不用it。There is something wrong with 有毛病There is no doubt of/that 无疑There is no need for/to do 不需要做There is no denying 无可否认There is no hurry about 无需慌忙There is no difficulty in 在方面没有困难There is no help for 没有办法There is no difference between 没有区别 There is no lack of 有很多的，不缺乏There is no possibility of/that 没可能There is no room for 没有的余地There is no sense in 是没有意义的There is no sign of 没有的迹象There is no saying that 难以断言，很难说There is a chance that/of 很可能 There is a possibility that/of有可能There is a slim hope of 有微小的希望There is some difficulty in 在有困难There is some trouble in 在有麻烦There appears to be 似乎有 There seems to be似乎有，好像有There used to be （过去）常常有，原来这里有There was a time when从前曾经有一个时候There is evidence that 显然There is no probability of/that很难有/会