It作形式主語講解docPPT課件

1、 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. 動詞不定式動名詞從 句形式主語形式主語第1頁/共19頁什么是形式主語？什么是形式主語？形式主語是指不定式（短語）、動名詞（短語）或從句在某個句子中做主語時，通常把它們放在謂語動詞前，it作形式主語代替不定式、動名詞、從句，置于句首，而將真正的主語放在句尾。此時為保持句子結(jié)構(gòu)前

2、后平衡，避免頭重腳輕，it只起先行引導(dǎo)作用，本身無詞義。第2頁/共19頁It is easy to become addicted to smoking .it is no good crying over spilt milk. (覆水難收) It is amazing that at my age I am still fit .It 作形式主語作形式主語代替不定式、動詞代替不定式、動詞-ing-ing短語或從句短語或從句adjn+(for/of sb) to do sthdoing sth主語從句It be +第3頁/共19頁 1、It +be+形容詞形容詞 + （for sb.）不定不

3、定式短語式短語 、itit代替不定式短語代替不定式短語 例1：It is wrong to tell a lie. It為to tell a lie的形式主語 例2：It is difficult to climb a mountain. It為to climb a mountain的形式主語 例3：It is a good habit to do morning exercises. It為to do morning exercises 的形式主語第4頁/共19頁1、It + be + adj +(for sb. / of sb./名詞詞組) + to do sth. a:It +be +a

4、dj +for sb to do sth 該句型中的adj通常是表示事物的特點或特征的，如 difficult，hard，easy，impossible，necessary，important等時，用for；意為做某事時是. eg: It is necessary for college students to master at least a foreign language.第5頁/共19頁b、It+ be +adj+of sb to do sth 該句型中的adj通常用來表示人的性格特征或特點的，如 nice，good，bad，kind，silly，foolish，wise，cleve

5、r， careless，rude，brave，cruel，careful， grateful等時，要用 of。意為某人做某事,某人是. eg:It is foolish of you to give up such a good chance.第6頁/共19頁 c: It + be +名詞詞組名詞詞組+ +動詞不定式動詞不定式 eg. It is not a good habit to stay up too late. 常見句型： It takes/took sb. some time/money to do sth.第7頁/共19頁 2、It +be+動名詞短語動名詞短語 it代替動名詞代

6、替動名詞ing形式形式 常見句型常見句型：It is no good（use）doing sth. 例1：It is no use learning without thinking學(xué)而不思則罔=There is no use (in) learning without thinking.真正的主語為learning without thinking. 例2：It is no good crying over spilt milk. 真正的主語為crying over spilt milk.第8頁/共19頁 3、It + be + that從句 it代替that從句 a: It + be +a

7、dj.+that從句 （這是that從句中最常用的一種） 如若形容詞為如若形容詞為 important / necessary， good/wrong .表達(dá)一種要求，命令或者責(zé)表達(dá)一種要求，命令或者責(zé)備時，多使用虛擬語氣（備時，多使用虛擬語氣（should +V).第9頁/共19頁 1、It is time +that sb. +v-ed/ should do1、It is time +that sb. +v-ed/ should doeg. Its time that you went to bed =Its time that you should go to bed.2、Its nec

8、essary/ impossible/ important/ natural that sb. (should) do eg. Its important that we (should) keep the balance of nature.第10頁/共19頁 2. 2. It + be + V-ed(V-ed(過去分詞過去分詞) ) + + that從句從句 這類過去分詞有：這類過去分詞有：said, believed, expected, hoped, decided, reported等等,如：如： It is said that 據(jù)說據(jù)說 It is reported that 據(jù)報

9、道據(jù)報道 It is supposed that 據(jù)推測據(jù)推測 It is hoped that 希望希望 It is well known that 眾所周知眾所周知 It is generally considered that普遍認(rèn)為普遍認(rèn)為 It is suggested that 有人建議有人建議第11頁/共19頁eg:1、It is reported that 16 people were killed in the earthquake.2、It is said that he has come to Beijing. 第12頁/共19頁注意：注意：如果主句中的過去分詞是表示請求

10、，建議，命令等詞如：如果主句中的過去分詞是表示請求，建議，命令等詞如：suggested/ordered/demanded. 等時等時 that后的從句要后的從句要用虛擬語（用虛擬語（should + 動詞原形），動詞原形），should 可以??；常譯可以??；常譯為，為，“據(jù)建議；有命令）據(jù)建議；有命令） It is suggested that the meeting ( should ) be put off. It was ordered that we ( should ) arrive there in two hours. 第13頁/共19頁3. It + be + 名詞詞組名詞詞

11、組 + that從句從句這類名詞有：這類名詞有：a fact, a pity, a shame, an honour，a question等，如：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時注意：如若表示出乎意料之意時,從句一般用虛擬語氣常從句一般用虛擬語氣常譯為譯為“竟然竟然”。沒有這種意義時，則不用虛擬語氣。沒有這種意義時，則不用虛擬語氣。 eg:It is

12、 a pity that such a good thing ( should ) happen in your class. 第14頁/共19頁4 4、 It + + 不及物動詞不及物動詞 + + 主語從句主語從句 這類不及物動詞有：這類不及物動詞有：appearappear/s/seemeem/ /happehappen n等等譯為譯為“好像好像././碰巧碰巧/如：如：It seemed that he didnt tell the truth.It happened that I was out when he called.第15頁/共19頁練習(xí)題：練習(xí)題： 把下列把下列句子句子轉(zhuǎn)換為轉(zhuǎn)換為itit做形式主語的句子做形式主語的句子 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 trying again.) 3.When and