The use of “It”, 1.it作人称代词 1.1.it的最基本用法是作人称代词，主要指刚提到 的事物，以避免重复: Ningbo is a beautiful city, isnt it? 1.2.也可以指动物或婴儿(未知性别的婴儿或孩子): Is this your dog？No, it isnt. 1.3.也可指抽象事物: It was a great surprise to me when he did a thing like that,2.非人称代词it it有时并不指具体的东西，而泛指天气、时间、环境等，称为非人称的it： 2.1.指天气： It is a lovely day, isnt it? It is a bit windy. 2.2.指时间: It was nearly midnight when she came back. 2.3.指环境: It was very quiet in the caf.,2.4.指距离： It is half an hours walk to the city centre.,.引导词it 1. It is + 被强调部分 + that .,使用该句型有以下几点请注意： 强调句的谓语is或was永远用单数. It was yesterday that I met your father in the street,不管被强调部分是哪种状语，只能用that连接，不得使用where、when等连词. It was in the street that I met your father yesterday,被强调部分为人时，可用who(主格或宾格)和whom(宾格)代替that，用that也行。 It was your father that/whom /who I met in the street yesterday 2) It was I that/who met your father in the street yesterday 强调句中 也要注意主谓一致、人称一致和否定转移的问题。 It is they who are our friends It was not until ten oclock that we got home last night,注意不要混淆强调句和其他从句。It is wasthat为强调句标志，去掉后仍可组成一个完整的句子，只是没被强调,而其他从句一般不具备这一特征。 比较： 1) It was ten oclock when we got home last night我们昨晚到家时已十点了。 2) It was at ten oclock that we got home last night我们昨晚是在十点到家的。,要点点拔,第一句不是强调句，when不可改为that,因为去掉it was和that后，只能组成“We got home ten oclock last night”这样一个不完整的句子；第二句是强调句，that不可改为when,2. 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. = Not until she took off her dark glasses did I realize she was a famous film star. = I didnt realize she was a famous film star until she took off her dark glasses.,3. it 用作形式主语 3.1 代替主语从句 1）It is + adj. +that从句 It is clear ( obvious， true， possible certain.) that . “清楚（显然，真的，肯定）” It is very clear that hes round and tall like a tree. . It is important ( necessary， right， strange， natural.能用于这个句型的形容词有strange、wonderful、natural、good、proper、right、wrong、well、fortunate、important、necessary、useless、likely、probable、impossible等。有时可省去should而直接用动词原形。 ) that . 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。 It is important that we (should) learn English well.,2）.It is +v-ed +that 从句 It is said (reported， learned.) that . 据说（据报道，据悉）“。 It is said that he has come to Beijing. . It is suggested ( ordered /demanded/insisted/commanded. ) that . 主句中的过去分词是表示请求，建议，命令等词时，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） It is suggested that the meeting ( should ) be put off.,3）. It is a pity ( a shame . ) that . 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。 It is a pity that such a thing ( should ) happen in your class. It is a pity that he is ill.,4). It is time ( about time ，high time ) that . 该句型中that 后的从句应该用虚拟语气，值得注意的是常用过去时态表示虚拟常译为是（正是）的时侯 It is time that children went to bed. It is the first ( second . ) time that . “是第一（二）次”。 It is the first time I have been here. = This is the first time I have been here.,5). It happens (seems， looks， appears ) that. 该句型中it是形式主语，that 引导的是主语从句，主句中的happen ， seem等词是不及物动词。 It happened ( so happened ) that he met his teacher in the street. 碰巧. It seems that he will be back in a few days. 看来,3.2.作形式主语替代不定式 1). It takes sb. . to do sth. 做要花费某人 It took thousands of people many years to build the Great Wall. 2). It is kind ( of sb. ) to do sth. 主句中的形容词必须是能表示逻辑主语特征的形容词。 常见的有： bad ， brave ， careless， clever ， cruel ， foolish ，stupid ， wise wrong等。 这个句型可以改写为：sb. is kind to do sth. 。 It is kind of you to say so. = You are kind to say so. 3). It is necessary ( for sb. ) to do sth. 常见的形容词有： important， necessary， natural easy ， safe ，common ，normal ，hard ， difficult ,dangerous ， 等。 在中的形容词作表语可以用从句改写， 如： It is important for her to come to the party. = It is important that she (should ) come to the party.,It is no good (use ) doing sth. 该句型中的真正主语是动名词短语，主句中的表语可以是no good ， ( not any good ) ， no use ， ( not any use )。 It is no good learning English without speaking English. Its useless trying to argue with Shylock.,3.3.作形式主语替代ing形式,4. It 作形式宾语. We think it important to learn a foreign language. 该句型中的it 作形式宾语，为了记忆方便我们可称该句型为6123结构。 6指主句中常用的动词：think,believe,make,find,consider,feel； 1指的是形式宾语it； 2指的是宾补的两种形式：形容词或名词； 3指的是真正宾语的三种形式：不定式短语，动名词短语或that引导的宾语从句。 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.,五、特殊句型 1). It is . since .。 It is ( has been ) 5 years since his father died. 2). It is . when .。 “当的时候，是” It was 5 oclock when he came here.,3). It be . before . 该句型主句中的 it 指时间， 主句中的时态常是一般将来时或过去时两种时态主句中的表语多是long， not long ， 3 days ， 2 weeks 等表示时间段的词或短语，常译为“之后”。 It was 3 days before he went to Beijing. It will be not long before he finishes his job.,（7）It is/was + 时间 + since 从已多久了。 It is five months since