It作形式主语讲解.doc

1、,It做形式主语 主讲人：欧云塔娜, Its necessary for the young to master two foreign language., Its a waste of time talking to her any more., Its a pity that you missed the exciting football match.,动词不定式,动名词,从 句,形式主语,什么是形式主语？,形式主语是指不定式（短语）、动名词（短语）或从句在某个句子中做主语时，通常把它们放在谓语动词前，it作形式主语代替不定式、动名词、从句，置于句首，而将真正的主语放在句尾。此时为保持

2、句子结构前后平衡，避免头重脚轻，it只起先行引导作用，本身无词义。,It is easy to become addicted to smoking . it is no good crying over spilt milk. (覆水难收) It is amazing that at my age I am still fit .,It 作形式主语代替不定式、动词-ing短语或从句,adj p.p n,+,(for/of sb) to do sth doing sth 主语从句,It be +,1、It +be+形容词 + （for sb.）不定式短语,、it代替不定式短语 例1：It is

3、 wrong to tell a lie. It为to tell a lie的形式主语 例2：It is difficult to climb a mountain. It为to climb a mountain的形式主语 例3：It is a good habit to do morning exercises. It为to do morning exercises 的形式主语,1、It + be + adj +(for sb. / of sb./名词词组) + to do sth.,a:It +be +adj +for sb to do sth 该句型中的adj通常是表示事物的特点或特征的

4、，如 difficult，hard，easy，impossible，necessary，important等时，用for；意为做某事时是. eg: It is necessary for college students to master at least a foreign language.,b、It+ be +adj+of sb to do sth 该句型中的adj通常用来表示人的性格特征或特点的，如 nice，good，bad，kind，silly，foolish，wise，clever， careless，rude，brave，cruel，careful， grateful等时，要

5、用 of。意为某人做某事,某人是. eg:It is foolish of you to give up such a good chance.,c: It + be +名词词组+动词不定式 eg. It is not a good habit to stay up too late. 常见句型： It takes/took sb. some time/money to do sth.,2、It +be+动名词短语,it代替动名词ing形式 常见句型：It is no good（use）doing sth. 例1：It is no use learning without thinking学而

6、不思则罔=There is no use (in) learning without thinking.真正的主语为learning without thinking. 例2：It is no good crying over spilt milk. 真正的主语为crying over spilt milk.,3、It + be + that从句,it代替that从句 a: It + be +adj.+that从句 （这是that从句中最常用的一种） 如若形容词为 important / necessary， good/wrong .表达一种要求，命令或者责备时，多使用虚拟语气（should

7、+V).,1、It is time +that sb. +v-ed/ should do 1、It is time +that sb. +v-ed/ should do eg. Its time that you went to bed =Its time that you should go to bed. 2、Its necessary/ impossible/ important/ natural that sb. (should) do eg. Its important that we (should) keep the balance of nature.,2. It + be +

8、 V-ed(过去分词) + that从句,这类过去分词有：said, believed, expected, hoped, decided, reported等,如： It is said that 据说 It is reported that 据报道 It is supposed that 据推测 It is hoped that 希望 It is well known that 众所周知 It is generally considered that普遍认为 It is suggested that 有人建议,eg:1、It is reported that 16 people were

9、killed in the earthquake.2、It is said that he has come to Beijing.,注意： 如果主句中的过去分词是表示请求，建议，命令等词如：suggested/ordered/demanded. 等时 that后的从句要用虚拟语（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. It was ordered that we ( should ) arrive there in two hours.,3.

10、 It + be + 名词词组 + that从句 这类名词有：a fact, a pity, a shame, an honour，a question等，如： eg: 1、Its common knowledge that people cannt live without water . 2、Its a pity that you missed the exciting football match. 注意：如若表示出乎意料之意时,从句一般用虚拟语气常译为“竟然”。没有这种意义时，则不用虚拟语气。 eg:It is a pity that such a good thing ( should ) happen in your class.,4、 It + 不及物动词 + 主语从句 这类不及物动词有：appear/seem/happen等译为“好像./碰巧/如： It seemed that he didnt tell the truth. It happened that I was out when he called.,练习题：,把下列句子转换为it做形式主语的句子 1.He was rude to say so. (It was rude of him to say so.) 2.Trying again is of use. (It is of use