1、Discover Useful Structures【版本：新人教册别：选择性必修三】UNIT 2 HEALTHY LIFESTYLE目录页contentsLead-inObserve and DiscoverPractice and ApplyHomeworkLead-inLead inTask 1 Read the following sentences and analyze what part does the underlined part serve as in each sentence?1.To change bad habits is never easy.2.It took
2、 the surgeon three hours to finish my mothers lung surgery.3.To join the Peoples 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Lead inTask 2 Compare the following sentences and find the differences of th
3、e subjects.1.To change bad habits is never easy,even with many attempts.2.To prevent harmful habits like these from dominating a teenagers life is essential.3.After all,it is not easy to break bad habits.4.However,during this period,it can be easy for some of them to form bad habits.5.Howtousethecom
4、puterisaquestion.6.Whentogothere hasnotbeendecided yet.Lead in动词不定式作主语有三种形式：1.直接放在 _ 作主语；2.为了保持句子平衡，用_作形式主语，放在句首，把真正的主语动词不定式置于句后；3.和 _ 构成短语作主语。句首it疑问词SummaryIIObserve and DiscoverObserve and Discover1.To see is to believe.2.To do this is to cut the foot to fit the shoe.3.To say is one thing and to d
5、o is another.4.To make a detailed plan is a good idea to make it successful.从位置上看，动词不定式作主语，通常放在句首。当句子主语和表语都是非谓语时，通常要_，例如：To see is to believe.=Seeing is believing.保持一致保持一致Observation 1Discover 1Observe and Discover1.For him to admit his mistakes is not easy.2.For us to finish the composition in a qu
6、arter of an hour is really difficult.动词不定式作主语可以带上自己的 _，一般用for/of短语来表示。但此时多使用形式主语 it 来引起，使得句子保持平衡。例如，第2 2句可以改为：It is really difficult for us to finish the composition in a quarter of an hour.逻辑主语逻辑主语Observation 2Discover 2Observe and Discover1.To be working all day long is a bore.2.To have made the s
7、ame mistake twice is unforgivable.3.To love and to be loved is the great happiness.动词不定式作主语可以有不同的_形式，例如，_，_和_语态。时态和语态时态和语态Observation 3Discover 3一般进行时一般进行时完成时完成时被动被动Observe and Discover1.It isnt right to talk like that.2.Its difficult to master English.3.Its hard for me to answer the question.4.It i
8、s better to have loved and lost than never to have loved at all.以上四个句子有两点共同之处：1.句子的真正主语都是_，但都使用it作形式主语；2.句子的表语都是_。动词不定式动词不定式形容词形容词it+be+adj+(逻辑主语逻辑主语)+to do sth Observation 4Discover 4Observe and Discover动词不定式的逻辑主语常用_ _ 来表示，当形容词修饰动词不定式时，此时常用介词_。当表语形容词表示不定式的逻辑主语的性质或特征时，则用介词_。1.It isnt right for us to
9、 stop half way.=To stop half way is not right.2.Its kind of you to think so much of us.=You are kind to think so much of us.for/of+sb forofObservation 5Discover 5Observe and Discover1.Its our duty to do that.2.Its a mistake not to help them.3.It must be great fun to fly to the moon in a spaceship.以上
10、三个句子的表语都是 _，它们可归纳为一个共同句式：_。名词名词 it+be+n+to do sthObservation 6Discover 6Observe and Discover1.It took me more than an hour to do my homework yesterday evening.2.It will take us a long time to walk there.3.How long does it take to get there?4.How much did it cost you to send the package?Observation 7
11、Discover 7以上四个句子是动词不定式作真正主语，由 it 作形式主语引导的句子，它们的谓语是 _。它们的共同句式是_，表示某人花多少时间或金钱做某事。take/costit takes(costs)sb some time/money todosthObserve and Discover1.How to use the computer is a question.2.Where to put the bikes is being discussed.3.When and where to have the meeting has not been decided._和动词不定式构成
12、不定式短语作主语。疑问词包括疑问代词who、whom、what、which、whose以及疑问副词when、where和how。此外连接词whether也适用。此时，疑问词 +to do 结构可以转化为一个_，例如：How to use the computer is a question.=_疑问词疑问词主语从句主语从句How we can use the computer is a question.Observation 8Discover 8动名词作主语表示_的行为;不定式作主语表示 _动作。Further thinking1._(do)morning exercises regula
13、rly is good for your health.2.It feels really good _(do)morning exercises today.Doingto do 经常性或习惯性经常性或习惯性具体的、一次性的或将来的具体的、一次性的或将来的Complete the following sentences and compare their usages.ConclusionPractice and ApplyPractice and Apply1.How long does it take for you _(get)there by bike?2.How much did
14、it cost you _(send)the package to Beijing?3.Its important _ you to walk after supper.4.Its very rude _ you to turn your back to your teacher and refuse to answer.在空白处填入在空白处填入1个适当的单词或括号内单词的正确形式。个适当的单词或括号内单词的正确形式。to get to send for ofPractice and Apply5.To make friends with these naughty boys _(be)nic
15、e.6.When _(hold)the meeting has not been discussed yet.7.It seemed a pity _(waste)so much time on the task without achieving our goal.8.To change or _(change)is a question we have to think about every day.to holdis to have wasted to be changed Practice and Apply 1.明天是否下雨，无关紧要。2.车不用时，及时锁好很有必要。3.这个老人对
16、蛇的怜悯导致了他的死亡。It doesnt matter whether to rain or not tomorrow.It is necessary to lock your car in time when not using it.The old mans taking pity on the snake leads to his death.For the old man to take pity on the snake leads to his death.翻译句子。翻译句子。4.减少工业污染，清洁水质，花费了多年工作才完成。5.对于像这样的一家公司，雇用安保人员是标准做法。Pr
17、actice and ApplyIt took years of work to reduce the industrial pollution and clean the water.Its standard practice for a company like this one to employ a security officer.在空白处填入1个适当的单词或括号内单词的正确形式。I had a variety of hobbies _ I studied in college.It was hard for me _(save)much money to keep my hobbi
18、es and it was also foolish _ me to spend plenty of time on those because it has been my dream _(be)a doctor.However,to become a doctor requires much study and it was a pity for me _(leave)behind because I _(waste)too much time keeping my unwise hobbies.Practice and Applywhen/whileto saveof to be to
19、be left had wasted Practice and ApplyFortunately I met my dear teacher,Miss Liu,who really changed my life course.After _(realize)my mistakes,I decided to make up for the lost time._(study)hard became my first task then _ to get up early every day turned to be my habit._ took me two terms to catch up with my classmates finally.realizingTo study andItHomeworkHomework1.Review what you have learned today.2.Draw mind maps of the infinitives usages as the subject.3.Make up a short story,using the infinitive as the subject as many as possible.
