It作形式主語(yǔ)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(dòng)詞不定式動(dòng)名詞從 句形式主語(yǔ)形式主語(yǔ)第1頁(yè)/共19頁(yè)什么是形式主語(yǔ)？什么是形式主語(yǔ)？形式主語(yǔ)是指不定式（短語(yǔ)）、動(dòng)名詞（短語(yǔ)）或從句在某個(gè)句子中做主語(yǔ)時(shí)，通常把它們放在謂語(yǔ)動(dòng)詞前，it作形式主語(yǔ)代替不定式、動(dòng)名詞、從句，置于句首，而將真正的主語(yǔ)放在句尾。此時(shí)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(yè)/共19頁(yè)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(yǔ)作形式主語(yǔ)代替不定式、動(dòng)詞代替不定式、動(dòng)詞-ing-ing短語(yǔ)或從句短語(yǔ)或從句adjn+(for/of sb) to do sthdoing sth主語(yǔ)從句It be +第3頁(yè)/共19頁(yè) 1、It +be+形容詞形容詞 + （for sb.）不定不

3、定式短語(yǔ)式短語(yǔ) 、itit代替不定式短語(yǔ)代替不定式短語(yǔ) 例1：It is wrong to tell a lie. It為to tell a lie的形式主語(yǔ) 例2：It is difficult to climb a mountain. It為to climb a mountain的形式主語(yǔ) 例3：It is a good habit to do morning exercises. It為to do morning exercises 的形式主語(yǔ)第4頁(yè)/共19頁(yè)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(diǎn)或特征的，如 difficult，hard，easy，impossible，necessary，important等時(shí)，用for；意為做某事時(shí)是. eg: It is necessary for college students to master at least a foreign language.第5頁(yè)/共19頁(yè)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(diǎn)的，如 nice，good，bad，kind，silly，foolish，wise，cleve

5、r， careless，rude，brave，cruel，careful， grateful等時(shí)，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(yè)/共19頁(yè) c: It + be +名詞詞組名詞詞組+ +動(dòng)詞不定式動(dòng)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(yè)/共19頁(yè) 2、It +be+動(dòng)名詞短語(yǔ)動(dòng)名詞短語(yǔ) it代替動(dòng)名詞代

6、替動(dòng)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(yǔ)為learning without thinking. 例2：It is no good crying over spilt milk. 真正的主語(yǔ)為crying over spilt milk.第8頁(yè)/共19頁(yè) 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(shí)，多使用虛擬語(yǔ)氣（備時(shí)，多使用虛擬語(yǔ)氣（should +V).第9頁(yè)/共19頁(yè) 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(yè)/共19頁(yè) 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(bào)

9、道據(jù)報(bào)道 It is supposed that 據(jù)推測(cè)據(jù)推測(cè) 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(yè)/共19頁(yè)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(yè)/共19頁(yè)注意：注意：如果主句中的過去分詞是表示請(qǐng)求

10、，建議，命令等詞如：如果主句中的過去分詞是表示請(qǐng)求，建議，命令等詞如：suggested/ordered/demanded. 等時(shí)等時(shí) that后的從句要后的從句要用虛擬語(yǔ)（用虛擬語(yǔ)（should + 動(dòng)詞原形），動(dòng)詞原形），should 可以??；常譯可以省；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(yè)/共19頁(yè)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(shí)注意：如若表示出乎意料之意時(shí),從句一般用虛擬語(yǔ)氣常從句一般用虛擬語(yǔ)氣常譯為譯為“竟然竟然”。沒有這種意義時(shí)，則不用虛擬語(yǔ)氣。沒有這種意義時(shí)，則不用虛擬語(yǔ)氣。 eg:It is

12、 a pity that such a good thing ( should ) happen in your class. 第14頁(yè)/共19頁(yè)4 4、 It + + 不及物動(dòng)詞不及物動(dòng)詞 + + 主語(yǔ)從句主語(yǔ)從句 這類不及物動(dòng)詞有：這類不及物動(dòng)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(yè)/共19頁(yè)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(yǔ)的句子做形式主語(yǔ)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