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1、it的用法（1）编稿：牛新阁 审稿：王春霞概念引入小词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 i
2、n an afternoon. (代替that从句作主语)3. Its my birthday in two weeks time and Ill be 82 years old! (表时间)4. Your mother tells me that you started smoking some time ago and now you are finding it difficult 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
3、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, isnt it? 宁波是座美丽的城市，是不是？ It doesnt 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。 The baby is crying. It might be hungry. 婴儿在哭，或许饿了。 Someone is r
4、inging. Who might it be? 有人按门铃，可能是谁呢？ It must be my friend TomHe (不可用It) wants to see you 一定是我的朋友汤姆，他想要见你。2. 作非人称代词it用作无人称的主语，不指物，而表示时间、天气、气候、季节、距离等自然现象，或指事物的状态。What a long way it is from Beijing to London! （it 指距离） 从北京到伦敦是多么长的一段距离啊！ It was nearly midnight when she came back. （it指时间）她回来时快半夜了。It was
5、very quiet in the caf. （it指环境）咖啡馆里静悄悄的。Its early spring, but its already very hot. （前面的it指季节，后面的it指气温）刚是初春，但是已经很热了。If it hadnt been for the snow, we could have climbed over the mountain. （it指情况）要不是因为下雪，我们可能已经翻越了那座山。易误辨析区别it，one，it，that和which1. it指上文出现过的同一事物，而one则泛指与前面事物同属一类中的一个。This was the last dic
6、tionary in that bookstore. So I took it.（it特指前面提到的那本词典）这是那家书店最后一本词典，所以我买下了它。There are many dictionaries in that bookstore. So I bought one. （one泛指其中之一）那家书店有许多词典，所以我买了一本。2. that做代词替代前面提到的事物, 可数名词、不可数名词皆可。代替可数名词可以用the one替换。that的复数形式为those,只可替代可数名词复数,在句中相当于the ones。The head teacher in your class is yo
7、unger and more active than that in theirs.你们班的班主任比他们班的班主任年轻而且更活跃。The students who do best in the exam are not always those with the best brains.考试考得最好的学生并不总是那些最聪明的学生。3. that在并列分句中,可以替代前面某一个名词或整个句子内容,可用it替换.She heard a terrible noise, and that brought her heart into her mouth.她听见一个可怕的声音，让她的心跳到了嗓子眼。4.
8、 it和which都可以用来指某一件事，关键要看中间是否有并列连词，如果有就用it，反之用which。The Smiths bought a new house, but it will need a lot of work before they can move in.史密斯家买了一座新房子，但是搬进去之前还需要大量的工作。（it 指代前面提到的那所房子，此句的关键词是but，连接两个分句，it是分句的主语）The Smiths bought a new house, which will need a lot of work before they can move in.（因为没有连词
9、，不能用it；which代表先行词house在定语从句中作主语。）He was badly ill, and it made his mother worried. 他病了，那使他母亲很担心。（it指代“他病了”这件事，注意and。）He was badly ill, which made his mother worried.（which代表前面整个主句，在定语从句中作主语）【高清课堂：Unit 3语法精讲 it做形式主语】it作形式主语 it作形式主语和形式宾语时，一般称为引导词，引出特定的句型。it作形式主语,代替由不定式,动名词或从句表示的真正主语。不定式、动名词或从句都可以作主语，如
10、：To say is one thing, and to do is another. （不定式作主语）说是一回事，做是另一回事。Seeing is believing. 眼见为实。（动名词作主语）That he is a hero is true. (从句作主语)当主语过长时，就会有不平衡感，为了句子的平衡、美观，我们引入了引导词的概念。 1) 代替由不定式表示的真正主语句型：It is + adj. / n. +for/of sb. to do sth.It is impolite to talk loudly in public places. 在公共场合大声说话是不礼貌的。（it代替不
11、定式“to talk loudly in public places”）为什么形容词后有时用for，有时用of呢？仔细观察这两个句型：It is important (necessary, possible, impossible, easy, hard, difficult) for sb. to do sth.It is nice (cruel, kind, rude, wise, stupid, clever, foolish, polite) of sb. to do sth.我们可以得出这样的结论：当形容词只是修饰这件事时，用for sb.，我们可以称为“单层修饰”；如果形容词看上去
12、是修饰人的，而且事情做出来也肯定是这样的，即形容词既修饰人，也修饰物时，用of。例如：我们学英语很重要。Its important for us to learn English.important是修饰“我们”，还是修饰“学英语”这件事呢？修饰“学英语”这件事，所以用for。再如：你帮助我真好。Its very kind of you to help me. 第一，“你”是好的；第二“帮助我”这件事也是好的，所以双重修饰就用of。2）可代替动名词表示的真正主语。 Its no use crying over spilt milk. 覆水难收。Its no good taking in muc
13、h fat and sugar. 吸收过多的脂肪和糖没有好处。Its no fun watching the same movie for a second time. 同一部电影再看一遍没有意思。 这里crying.等动名词短语是真正的主语，it代替它们作形式主语。这些句型与前面的句型类似，那么什么时候要加-ing形式呢？我们只需记住，动名词的这种句型是比较少的，记住一些固定用法即可，如在高考中经常出现的Its no use/ no good/ no fun doing sth. 做某事没有用/没有好处/没有意思。3）代替主语从句 Its a pity that I didnt think
14、of it earlier. 我没有早一点这么想真是遗憾。It is a well-known fact that smoking can cause cancer. 吸烟会引起癌症是尽人皆知的事实。it代替that引导的主语从句作形式主语。注意：选it还是as：It is well known to all that the earth is round. 众所周知，地球是圆的。这个句子中it代替that引导的从句作形式主语，经常会与下面这个定语从句的句型混淆：_ is well known to all, the earth is round.这个句子中，第一个典型特征是逗号，第二是逗号后
15、没有that，也就没有形式主语了。空白处应该填As。As代替后面的句子“the earth is round”，在定语从句中作主语。这两种形式要清晰地记住。 4）注意以下固定句型：It seems (ed) / appears (ed) that . 似乎.It (so) happened that . 碰巧.It turns (ed) out that. 结果是It occurred to sb. that . 某人突然想起.It is said / reported / believed / hoped / well known / suggested . that. 据说/据报道/大家都相信/人人都希望/大家都知道/有人建议. 例如：It so happened that the tickets were sold out. 碰巧票都卖光了。It occurred to her that
