(
课件网) （人教版）选择性必修三U2 Period 3 Discouver useful structures Healthy lifestyle Unit2 Learning objectives By the end of the lesson, I will be able to... 01 02 03 04 Master the three common forms of the infinitive (to do) as the subject. Tell apart the sentence patterns with it as the formal subject for to do. Use wh-word + to do phrases correctly as the subject in sentences. Apply the to do as subject in exercises and simple conversations. A brief review：complete the sentence The duty of the soldiers is _____(defend) their country. Several problems remain _____(settle). The question is how _____(carry) out the plan. All he wants is _____(buy) a bicycle. to defend to be settled to carry to buy to do 作表语 What about the following ones What’s the functions of “to do” in the sentences 1 To change bad habits is never easy. 2 It took the surgeon three hours to finish my mother’s lung surgery. 3 To join the People’s Liberation Army , it is required for men to shave off their beards. 4 It was not polite to disturb your neighbours with loud music last night. 主语 主语 目的状语 主语 主语 动词不定式作主语常见的三种形式 1. 不定式作主语通常位于句首，表示具体的某次动作. To see is to believe. To get up early is necessary. To work out the problem is not easy. =It’s not easy to work out the problem. 2.当主语较长，谓语较短时，常用it作形式主语放在句首，而将真正的主语—不定式放到谓语的后面。 动词不定式作主语常见的三种形式 It is necessary for you to change your job. It’s very kind of you to say so. It must be great fun to fly to the moon in a spaceship. It will take us a lot of money to buy that house. It is + adj. + for sb. to do sth. (adj.修饰物) It is + adj. + of sb. to do sth. (adj.修饰人) It is + n. + (for sb.) to do sth.（pity/shame/fun/joy/pleasure...） It takes/took/will take sb. some time/money to do sth. it作形式主语代替真正主语不定式常见于以下情况中： 3. 动词不定式与疑问词who, whom, whose, what, which, when, where, how等连用构成不定式短语，也可作主语。 How to use the computer is the question. Where to go _____(have) not been decided. Where and when to go on a holiday _____(have) not been decided. 如何开始比到哪里停止还困难。 _____ _____ _____ is more difficult than _____ _____ _____. 动词不定式作主语常见的三种形式 has has How to start where to stop 基础填空题用所给词的适当形式填空 （穿插分词）1. _____ (learn) a foreign language requires patience.2. It is important _____ (keep) calm in an emergency.3. _____ (swim) in the lake is dangerous.4. How _____ (improve) my writing skills is my biggest concern.5. It took her three hours _____ (prepare) for the party.To learn/Learningto keepSwimmingto improveto prepare基础填空题用所给词的适当形式填空 （穿插分词）6. _____ (not give) up is the key to success.7. What _____ (do) next is still under discussion.8. _____ (read) aloud every morning helps with pronunciation.9. It is necessary _____ (obey) the school rules.10. _____ (wait) for others mak ... ...
