Unit2AHealthyLifestyle不定式做主语课件高中英语人教版选择性

选择性必修三Unit2DiscoveringusefulstructuresTheinfinitiveoftheverbusedasthesubject动词不定式作主语HealthyLifestyleFocuson基本用法不定式作主语一、通常用法二、*it作形式主语的用法*it作形式主语时的三种情况三、“疑问词+动词不定式”作主语1.不定式作主语通常位于句首，表示具体的、某一次的或将来的动作，谓语动词用单数。Toseeistobelieve.Togetupearlyisnecessary.Tofinishthebuildinginamonthisdifficult.一【含义】

不定式作主语通常表示一个将来的、具体的内容;而动词-ing形式则表示一种经常性的、习惯的或抽象的概念。Tolookafterchildrenisherjobtoday.她今天的工作是看孩子。Lookingafterchildrenisherwork.她的工作是照顾孩子。不定式作主语和动词-ing形式作主语和动词的区别：[巧学活用1]——单句语法填空①________(finish)readingthebookwilltakeyoutwohours.②________(pay)avisittotheForbiddenCityismydream.③Toimprovepeople'slivesandtospeedupsocialistconstruction_____(be)twoimportanttaskstoday.④________(stay)uptoolateisabadhabitforourhealth.TofinishTopayareStaying2.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。Toworkouttheproblemisnoteasy.=It’snoteasytoworkouttheproblem.Toplaywithsnowinwinterisinteresting.=Itisinterestingtoplaywithsnowinwinter.Tofinishthebuildinginamonthisdifficult.=Itisdifficulttofinishthebuildinginamonth.考点：it作形式主语常见的句型1.Itis+形容词+for/ofsb+todosthE.g.Itiseasyformetolearnhowtodrive.Itiscleverof

youtoapplyfortheposition.一般规律：若形容词”描述人的属性，特征”,用of;若形容词“描述事或物的特征”,

用for;

Exercises2、接名词作表语：Itis+n.+todosth.Itmustbegreatfuntoflytothemooninaspaceship.

乘宇宙飞船飞往月球一定很有趣。Itisapity

foryou

tomisssuchawonderfulfilm.

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“Ittakessb.sometime/moneytodosth.”句型中。It

tookmemorethananhourtodomyhomeworkyesterdayevening.昨天晚上我做作业用了一个多小时。Itwilltakeusalotofmoneytobuythathouse.买那套房子要花费我们很多钱。做某事花费某人多长时间(钱)[巧学活用2]——单句语法填空①[2022·新高考卷Ⅰ应用文]Itismypleasure________(invite)youtoourEnglishshow“TalkandTalk”whichwillbeconductedat6a．m.thisFriday.②Itisgoodmannersfortheyoung________(give)theirseatstotheold.③Itismyambition________(make)surethatthedisabledpeoplehaveaccesstoallpublicbuildings.④Itisnouse________(argue)withhim,forheissostubborn.toinvitetogivetomakearguing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，疑问代词：who，whom，what，which疑问副词：when，where，howwhetherE.g.Howtobreakthebadhabitisthequestion.Wheretogohasn'tbeendiscussed.IthasnotbeendecidedwhethertoflytoParis.

3.”疑问词+todo”作主语

[巧学活用3]——单句语法填空①How________(cure)thiskindofillnessisstillunknown.②Whether________(do)itornothasnotbeendecided.③How________(deal)withthiscasehasn'tbeenknownyet.tocuretodotodealI.Choosethebestanswer.1、It’sourduty______theroomeveryday.A.toclean B.cleanedC.clean D.cleans2、It’shardforus_______Englishwell.A.learnB.learnsC.tolearnD.learning3、It’sverynice___youtogetmetwotickets____theWorldCup.A.for,ofB.of,

forC.to,

forD.of,

to1.Itisveryhelpfulforallofus________(help)agoodknowledgeofhistory.2.It’snecessaryforyou________(lock)thecarwhenyoudonotuseit.3.Afraidof___________(bite)bysnakes,theboywasafraid________(touch)them.4.________(get)therebybikewilltakeushalfanhour.PraticetohelptolockbeingbittentotouchTogetⅢ.Translation.1.早起是必要的。2.对我们来说，完成这项工作很困难。3.如何控制水污染是一个大问题。4.