Unit 2 Healthy lifestyle Discover useful structures （ppt课件）-2023新人教版（2019）《高中英语》选择性必修第三册.pptx

1、Lead-inPresentationpracticeproductionPart 1 Lead-inWords review1.rely on 依赖；依靠；reliable adj.可信赖的；2.straight away 立即，马上3.pessimistic 悲观的 optimistic 乐观的4.arrive at/come to/reach a decision作出决定5.make up ones mind to do sth.下定决心做某事 bear/keep sth.in mind 牢记某事6.be compose of 由.组成7.in response to答复；回答8.dec

2、ide on 决定；选定Pay attention to the sentencesIt is difficult for me to get up early.It is kind of you to help me!To get up early is difficult for me.To help me is kind of you!to do 作主语1.To change bad habits is never easy2.To change or to be changed is a question we have to think about every day.3.When

3、and how to go there has not been decided yet.作主语的是动词不定式，谓语动词用动词不定式，谓语动词用单数单数.Think:系动词前的habits为复数,为何谓语动词用is？1.To prevent harmful habits like these from dominating a teenagers life is essential.2.To change bad habits is never easy,even with many attempts.3.However,during this period,it can be easy fo

4、r some of them to form bad habits.4.After all,it is not easy to break bad habits.5.When there has not been decided yet.【总结】1.1-4句子中动词不定式都是作句子中动词不定式都是作_语。语。2.句句3和句和句4中中it作作_，真正主语是后面的，真正主语是后面的_。3.句句5中是中是_+不定式作主语不定式作主语 主 形式主语 to do疑问词Part 2presentation1.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

5、；3.和_构成“疑问词+to do”短语作主语。句首it疑问词动词不定式作主语用法有三个：1.To clean the window is todays job.2.To jump out of the window is dangerous.3.To finish the work before Friday is not so easy.一、一、不定式不定式直接放在句首作主语直接放在句首作主语 以上句子中动词不定式（短语）在句中直接作_(成分)。注意1：谓语动词采用_ 形式。注意2：不定式做主语与动名词做主语的区别一般来说，不定式做主语，表示具体的、一次性的或将来的动作；具体的、一次性的或

6、将来的动作；动名词做主语，表示一般的、泛指的或习惯性一般的、泛指的或习惯性的行为的行为。但是在多数情况下无明显区别。如To see is to believe.=Seeing is believing.练习：_(teach)English is my job._(teach)you English this term is my job.To say is one thing and _(do)is another.To change bad habits _(be)never easy,even with many attempts.to doTo teach三单主语Teachingis不定

7、式作主语用法不定式作主语用法 单个不定式作主语，谓语动词用_ 两个或两个以上的不定式作主语，若语意一致或作为一个整体，谓语动词用_ 两个或两个以上的不定式作主语，若语意不一致，谓语动词用_单数单数复数补充：主谓一致二、二、it 作形式主语放在句首，后面的不定式作真正的主语作形式主语放在句首，后面的不定式作真正的主语1.It is interesting to play with snow in winter.2.Its important for us to keep the water clean.3.Its very kind of you to help me.4.It must be

8、great fun to fly to the moon in a spaceship.5.It took me more than an hour to do my homework yesterday evening.6.It appears unlikely to come back in half an hour.以上5个句子中动词不定式在句中均作_成分。It is possible _(walk)or bike the entire 14 kilometers.She admits _ took her a while to come around to the opinion.It

9、 is a great fun _ him to leave for the other city to work.It seemed selfish _ him not to share his dictionary with others.offoritto walk主语不定式作主语用法不定式作主语用法1.It is+adj.+for/of sb+to do sthu 若adj.”描述人的品格、特点”,用of,如 kind，polite，impolite，rude，foolish;u 若adj.“描述事或行为的特征”,用for,如difficult,possible，necessary 归

10、纳：it作形式主语常见句型 It is stupid _them to quarrel about this question.It is easy _ me to learn how to drive.It is impolite _ him to say so.It is important _ us to express our opinions.It is clever _ him to leave that company.2.It is+名词(a pleasure/a pity/an honour.)(for sb)+to do sthE.g.u It is an honour t

11、o give a speech in behalf of my school.u It is a pity to miss the chance to see your show.3.It takes/took/will take sb.some time/money to do 做某事花费某人多长时间/钱E.g.u It took me more than an hour to do my homework yesterday evening.归纳：为保持句子平衡，用为保持句子平衡，用it来作形式主语来作形式主语,相关句型有：相关句型有：It is/was形容词形容词(for/of sb)动

12、词不定式动词不定式形容词修饰动词不定式这件形容词修饰动词不定式这件事事时，此时常用介词时，此时常用介词for。形容词修饰形容词修饰表不定式的表不定式的逻辑主语逻辑主语时，则用介词时，则用介词of。It isa/an名词名词(如如a pity/an honour.)to do.It takes/costs/requires.sb/sth to do sth1.浪费时间做某事:It is a waste of time doing sth2.做某事是没有用的 Its no use/no good doing sth Its useless doing sth It is fun/no fun do

13、ing sth 复习：it作形式主语doing作真正的主语 _(complete)todays homework is a little bit difficult for me.比较 _(read)is my hobby,which nearly takes up all my spare time.ReadingTo complete三、三、“特殊疑问词特殊疑问词+不定式不定式”作主语作主语1.How to use the computer is a question.2.Where to go has not been decided.3.When to start hasnt been

14、 decided yet.4.Whether to drive or take a taxi is still a question.以上例句谓语动词都是用的_ 形式。Where and when _(cast)a net is more important than how to cast a net.Whether to compete in the relay race _(be)a decision that has to be made by our teacher.How the work should be finished is still a question.=How _

15、the work is still a question.三单to castisto finish不定式作主语用法不定式作主语用法归纳 不定式作主语，有时根据表达的需要，可以在添加疑问代词或副词，u 疑问代词：who，whom，what，which u 疑问副词：when，where，how u whether疑问词疑问词+to do可作主语可作主语,相当于一个相当于一个主语从句主语从句。疑问词包括疑问词包括疑问副词疑问副词when、where和和how及及疑问代词疑问代词who(m)、what、which、whose。连接词。连接词whether也适用。也适用。Part 3Practice1

16、._(look)after the safety of the community is his responsibility.2.How _(cure)this kind of illness is still unknown.3.It seemed selfish of him _他不给员工任何东西，这显得他太自私了。4.It seems a pity _拒绝这邀请似乎是遗憾的5.Its unwise _他们拒绝(采纳)这个建议是不明智的。1.It took us about two hours_(get)there that day.2.It is no use _(argue)with

17、 him，for he is so stubborn.3.解决这个具有挑战性的问题非常难。_(动词不定式作主语)_.(it作形式主语)To lookto curenot to give his employees anythingto refuse the invitation of them to turn down the proposalto get arguing To solve the challenging problem is quite difficult.It is quite difficult to solve the challenging problem.1.Its

18、 a great honour _ to Marys birthday party.被邀请参加玛丽的生日派对是一件很荣幸的事情。2.It is difficult for us_ 我们难以在15分钟内写完这篇作文。3.It is stupid of you_ 你把老师说的所有都记下来是愚蠢的。4._，and it is hard work that can change your present terrible situation.哭没有用，而且只有努力才能改变你现在糟糕的处境。5.It is a great honour for me _ on how to get along well

19、with your parents.我很荣幸与你分享如何与你父母和睦相处的观点。to be invited to finish writing the composition in a quarter of an hour to write down everything the teacher says It is no use cryingto share with you my opinions1._ took us a long time to repair the house.2.It is foolish _ you to turn down the proposal(提议).3.

20、It is important _ her to prepare for the examination.4.When you are in trouble,it is _(help)to turn to your teacher.5.To form a good habit _(be)difficult while to fall into a bad habit is easy.6.Whether _(hold)a party this weekend hasnt been known yet.（1）Sometimes its better （remain）silent.（2）Althou

21、gh is a hard task to protect our environment，we cant help but go ahead.（3）（control）the air pollution is necessary.（4）It was foolish him to endanger his life in that way.（5）Dont you think it is rude him to ask a lady her age?（6）It is difficult him to live on such a small salary.to remain it To contro

22、l/Controlling of of for 5.To make friends with these naughty boys _(be)nice.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 was

23、ted to be changed 1.How long does it take for you _(get)there by bike?2.How much did 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.to get to send for ofPart 4Production1.important/avoi

24、d/passive cigarette smoking It is important to avoid passive cigarette smoking.2.will take/nutrition specialist/a balanced diet menu/make/an hour/for you_It will take an hour for a nutrition specialist to make a balanced diet menu for you.3.useful/turn to/fitness consultant/for advice_4.illegal/dang

25、erous/take/drugs_5.harmful/skip breakfast/often_It is harmful to skip breakfast(too)often.It is useful to turn to a fitness consultant for advice.It is dangerous to take illegal drugs.to do作主语to do 作主语位于句首，位于谓语之前to do 作主语位于谓语之后，it作形式主语疑问词+to do 构成不定式短语，作主语To read without reflecting like eating without digesting.It takes sb.time/money to do sth.It is+adj.+（for/of sb.）to do sth.It is+n.+(for sb.)to do sth.与疑问词who,whom,whose,what,which,when,where,how等连用