【正文】 hing TV.　　看電視是浪費時間。（= He was foolish to give up the job　?、?it代替動名詞短語：　　動名詞作主語用后置形式的情況遠不及不定式那么普遍，常限于no good, no use, useless, waste等詞的后面。　?、跧t’s kind of you to help me.　　感謝你對我的幫助。（ it作形式主語, 代替不定式短語to build the bridge）　　◆ It be + 形容詞+ for sb. to do be + 形容詞+of sb. to do sth.：　　、品格，否則就用for?！　。?it作形式主語, 代替不定式短語to learn Chinese）　?、跧t is not right to use these places as rubbish dumps.　　把這些地方用來倒垃圾是不對的。　?、?it代替不定式短語　　常用于下列句型中：It + be +形容詞 + (for/of sb.) 　　to do sth.　　It + be + 名詞 + to do sth.　　It takes sb. some time to do sth. 干…花了某人…時間　　It’s up to sb. to do sth. 干…是某人的職責或義務(wù)　　　①It is everyone’s duty to obey the law.　　遵守法律是每個人的義務(wù)。it作形式主語：　　it作形式主語時沒有具體的意義，而只是幫助把真正的主語移到句子后部去，使句子顯得平穩(wěn)一些。如：It’s very kind of you to help me with the work.=You are kind to help me.It seemed selfish of him not to share his dictionary with others.=He seemed selfish not to share his dictionary with others.7. It + be +名詞詞組 + 動詞不定式，如：It is not a good habit to stay up too late.8. It + be + 名詞或形容詞 + 動名詞，這類名詞和形容詞常常是：good, no good, no use, a waste of, useless, senseless等，如：It’s a waste of time talking to her any more.It is no use arguing about the matter with him.9. It + take ( sb. )+ 時間（金錢）+ 動詞不定式，如：It took the workers almost three years to finish building the dam.It will take a whole day to get to the top of the mountain on foot.實戰(zhàn)演練：1. It is generally considered unwise to give a child he or she wants. (NMET 1997)A. however B. whatever C. whichever D. whenever2. In fact is a hard job for the police to keep order in an important football match. (2001 上海)A. this B. that C. there D. it3. is a fact that English is being accepted as an international language. (NMET1995)A. There B. This C. That D. It 4. Is necessary to take off our shoes when we enter the lab? (MET88) A. everyone B. this C. her D. it5. ________ will take you a lot of time to find him in the crowd. A. It B. I C. We D. They6. It is no use his _________ there, the situation is hopeless now. A. to go B. to be going C. going D. having gone7. It is never too late to learn, ________? A. is it B. isn’t it C. does it D. doesn’t it8. ___________ is known to all that Shenzhou VI Launched Successfully. A. As B. What C. It D. That 9. _______ is reported in the newspaper, the Earthquake in east China39。It作形式主語常見句型動詞不定式，動名詞或主語從句作主語時，通常把它們放在謂語動詞前，而用it作形式主語，放到句首，常見句型有：1. It + be + 形容詞+主語從句，如：It is uncertain whether he can e to Jenny’s birthday party or not.2. It + be + 名詞詞組 + 主語從句，這類名詞有：a fact, a pity, a shame, an honour，a question等，如：It’s a pity that you missed the exciting football match.It remains a question whether he will e or not. 3. It + be + 過去分詞 + 主語從句，這類過去分詞有：announced, believed, expected, hoped, decided, reported, said, shown等， 如：It is reported that 16 people were killed in the earthquake.It is not decided who will give the operation to the patient.4. It + 不及物動詞(seem, appear, happen等) + 主語從句, 這類不及物動詞有：appear, happen, seem等， 如：It seemed that he didn’t tell the truth.It happened that I was out when he called.5. It + be + 形容詞 + for sb.）+ 動詞不定式這類句型常用形容詞easy, difficult, hard, important, possible，wise等作表語，有時候為了強調(diào)不定式動作的執(zhí)行者，常在不定式前加for sb，如：It’s necessary for the young to master two foreign language.It is unwise to give the children whatever they want.這類形容詞有：easy, difficult, hard, important, possible，wise 6. It + be + 形容詞 + of sb. + 動詞不定式，這類形容詞常是表示心理品質(zhì),性格特征的形容詞，如：kind, nice stupid, clever, foolish, polite, impolite, silly, selfish, considerate等。某人和這些形容詞可以構(gòu)成主系表結(jié)構(gòu)。s Jiangxi Province killed 13 people A. It B. As C. That D. What10. ___________ certain that his invention will make people’s life convenient. A. That’s B. This is C. It’s D. What’s11. _________ that there is another football match on the air this evening. A. It says B. It was said C. It is said D. What was said12. __________ that their daughter got an opportunity to study abroad. A. It’s a exciting news B. This is an exciting news C. This is exiting news D. It’s exciting news參考答案：1——5 BDDDA 6——10CACAC 11——12CD㈠ it作形式主語時，可以代替三種形式：不定式、動名詞和主語從句。（ it作形式主語, 代替不定式短語to obey the law）　?、贗t is difficult for a foreigner to learn Chinese.　　對于一個外國人來說，學習漢語是困難的?！　。╥t作形式主語, 代替不定式短語to use these places as rubbish dumps）　?、躀t took them a year to build the bridge.　　建這座橋花了他們一年的時間?！　、買t’s necessary for us to use a shortwave radio to pick up the programmes.　　我們用一臺短波收音機收聽這些節(jié)目是必要的。（= You are kind to help me. ）　?、躀t was foolish of him to give up the job.　　他放棄那工作是愚蠢的。　　 　?、買t is no good/ use having a car if you can’t drive.　　如果你不會開車，有車也沒用。（ it作形式主語,代替動名詞短語watching TV）　　③It is no use asking him.　　問他沒有用?！　、買t was clear that they had no desire for peace.　　很清楚他們沒有和平的誠意。（ it作形式主語,代替主語從句whether she will be able to e）　?、跧t was clear enough what she meant.　　她的意思是夠清楚的?！　、贗t is a wonder that he continues to gamble when he always loses!　　令人驚訝