Unit 2 Discover useful structures 不定式做主语(ppt课件)-2022新人教版（2019）《高中英语》选择性必修第三册.pptx

1、Unit 2 Learning About LanguageDiscover useful structuressurgeonsurgeryliberationshaveshave offdisturbcigarettespecialistconsultantdrugskipn.外科医生外科医生n.外科手术；外科学外科手术；外科学n.解放；摆脱解放；摆脱vt.,vi&n.剃剃（须发）（须发）；刮脸；刮脸剃掉；刮去剃掉；刮去vt.打扰；搅乱；使烦恼打扰；搅乱；使烦恼n.香烟；卷烟香烟；卷烟n.专科医生；专家专科医生；专家n.顾问；高级顾问医师顾问；高级顾问医师n.毒品；药物毒品；药物vt.跳过跳

2、过;不参加；悄悄溜走不参加；悄悄溜走vi.蹦蹦跳跳地走；跳绳蹦蹦跳跳地走；跳绳n.蹦跳蹦跳Read after the tape and speak out the Chinese immediately.Learning objectives:1.To know the different forms of the infinitive;2.To master the use of the Infinitive as subject;3.To use the Infinitive as subject in the specific context correctly.Focus on Fo

3、cus on 基本用法基本用法不定式作主语不定式作主语一、通常用法一、通常用法二、二、*itit作形式主语的用法作形式主语的用法 *itit作形式主语时的三种情况作形式主语时的三种情况三、三、“疑问词疑问词+动词不定式动词不定式”作主语作主语 To see is to believe.百闻不如一见。百闻不如一见。To get up early is necessary.早起是必要的。早起是必要的。一、通常用法 不定式作主语不定式作主语通常通常位于句首位于句首，表示，表示具体的某次动作，具体的某次动作，谓语动词用单数谓语动词用单数。it为形式主语为形式主语动词不定式为真正的主语动词不定式为真正的

4、主语Observe these sentences and think about what it refers to.当主语是动词不定式短语时，当主语是动词不定式短语时，为避免头重为避免头重脚轻，一般用代词脚轻，一般用代词 it it 作形式主语放在句首作形式主语放在句首，而将而将真正的主语放在句末真正的主语放在句末。二、二、itit作形式主语：作形式主语：1、It is+adj.+for sb.to do sth.It s important for us to keep the water clean.保持水质清洁对我们来说是很重要的。It is+adj.+of sb.to do sth

5、.Its very kind of you to say so.你这样说真是太好了。此处adj.表示事物的特征，常见的有：easy,difficult,possible，nice 等 此处adj.表示sb.的性质、特征或品德，常见的有：kind,polite,friendly,silly 等即时演练(1)你真是粗心，把伞忘在了火车上。_ your umbrella in the train.(2)看到刚才发生的事情，我被震惊到了。_ what happened just now.(3)一位妈妈担心她的孩子这是很自然的。_ her own children.It was careless of

6、you to leaveIt shocked me to seeIt is natural for a mother to worry about2、接、接名词名词作表语：作表语：It is+n.+to do sth.It must be great fun to fly to the moon in a spaceship.乘宇宙飞船飞往月球一定很有趣。It is a pity for you to miss such a wonderful film.你错过了这么好的电影，真可惜。3.it作形式主语时，还常用于作形式主语时，还常用于“It takes sb.some time/money

7、to do sth.”句型中。句型中。It took me more than an hour to do my homework yesterday evening.昨天晚上我做作业用了一个多小时。It will take us a lot of money to buy that house.买买那套房子要花费我们很多钱。套房子要花费我们很多钱。做某事花费某人多长时间做某事花费某人多长时间(钱钱)疑问词疑问词 how,what,when,where,which+不定式短语作主语，置于句首不定式短语作主语，置于句首，谓语动词用谓语动词用单数单数。How to use the computer

8、 is the question 如何使用计算机是个问题。Where to go has not been decided 去哪儿还没有定下来。三、疑问词不定式三、疑问词不定式即时演练(1)步行去银行大约用十分钟时间。_.(2)做什么还没有确定。_.(3)建造这座桥将花费工人们一年多的时间。_.It takes about ten minutes to walk to the bank What to do is not decided yet It will take the workers over a year to build the bridge.(read)English nove

9、ls is really interesting (read)English novels this evening will take most of my time.四、不定式与四、不定式与V-ingV-ing作主语的区别作主语的区别 不定式作主语表示一次性的、具体的或将来的动作，强调的是动作本身；动名词作主语表示一般的、抽象的、泛指的或者已经完成的动作，强调的是事情本身。ReadingTo read翻译句子(1)每天读书是个好习惯每天读书是个好习惯。_.(2)和他们交朋友真是令人愉快。_.(3)你能帮助我真是太好了。_.(4)晚饭后散步对健康有好处。_does good to your

10、health.Reading books every day is a good habitTo make friends with them is niceIts kind of you to do me a favour Walking after supper*通常位于句首；通常位于句首；*常用常用it作形式主语的句型结构：作形式主语的句型结构：It is+adj.+for sb.to do sth.It is+adj.+of sb.to do sth.It is+n.+to do sth.It takes(took/will take)sb.some time/money to do

11、sth.”*“疑问词疑问词+动词不定式动词不定式”作主语作主语*区别区别动词不定式作主语：动词不定式作主语：I.I.Choose the best answer.1、Its our duty _ the room every day.A.to clean B.cleaned C.clean D.cleans2、Its hard for us _ English well.A.learn B.learns C.to learn D.learning3、Its very nice _ you to get me two tickets _ the World Cup.A.for,of B.of,f

12、or C.to,for D.of,to1.It is very helpful for all of us _(help)a good knowledge of history.2.Its necessary for you _(lock)the car when you do not use it.3.Afraid of _(bite)by snakes,the boy was afraid _(touch)them.4._(get)there by bike will take us half an hour.to helpto lockbeing bittento touchTo get

13、.Translation.1.1.早起是必要的。早起是必要的。2.2.对我们来说，完成这项工作很困难。对我们来说，完成这项工作很困难。3.3.如何控制水污染是一个大问题。如何控制水污染是一个大问题。4.4.步行去那儿要花费我们很长时间。步行去那儿要花费我们很长时间。Its difficult for us to finish the work.How to control the water pollution is a big problem.It will take us a long time to walk there.To get up early is necessary.Finish the exercises in Learning English.