Unit2AHealthyLifestyle不定式做主語課件高中英語人教版選擇性

選擇性必修三Unit2DiscoveringusefulstructuresTheinfinitiveoftheverbusedasthesubject動詞不定式作主語HealthyLifestyleFocuson基本用法不定式作主語一、通常用法二、*it作形式主語的用法*it作形式主語時的三種情況三、“疑問詞+動詞不定式”作主語1.不定式作主語通常位于句首，表示具體的、某一次的或?qū)淼膭幼鳎^語動詞用單數(shù)。Toseeistobelieve.Togetupearlyisnecessary.Tofinishthebuildinginamonthisdifficult.一【含義】

不定式作主語通常表示一個將來的、具體的內(nèi)容;而動詞-ing形式則表示一種經(jīng)常性的、習(xí)慣的或抽象的概念。Tolookafterchildrenisherjobtoday.她今天的工作是看孩子。Lookingafterchildrenisherwork.她的工作是照顧孩子。不定式作主語和動詞-ing形式作主語和動詞的區(qū)別：[巧學(xué)活用1]——單句語法填空①________(finish)readingthebookwilltakeyoutwohours.②________(pay)avisittotheForbiddenCityismydream.③Toimprovepeople'slivesandtospeedupsocialistconstruction_____(be)twoimportanttaskstoday.④________(stay)uptoolateisabadhabitforourhealth.TofinishTopayareStaying2.當(dāng)主語較長，謂語較短時，常用it作形式主語放在句首，而將真正的主語—不定式放到謂語的后面。Toworkouttheproblemisnoteasy.=It’snoteasytoworkouttheproblem.Toplaywithsnowinwinterisinteresting.=Itisinterestingtoplaywithsnowinwinter.Tofinishthebuildinginamonthisdifficult.=Itisdifficulttofinishthebuildinginamonth.考點：it作形式主語常見的句型1.Itis+形容詞+for/ofsb+todosthE.g.Itiseasyformetolearnhowtodrive.Itiscleverof

youtoapplyfortheposition.一般規(guī)律：若形容詞”描述人的屬性，特征”,用of;若形容詞“描述事或物的特征”,

用for;

Exercises2、接名詞作表語：Itis+n.+todosth.Itmustbegreatfuntoflytothemooninaspaceship.

乘宇宙飛船飛往月球一定很有趣。Itisapity

foryou

tomisssuchawonderfulfilm.

你錯過了這么好的電影，真可惜。3.it作形式主語時，還常用于“Ittakessb.sometime/moneytodosth.”句型中。It

tookmemorethananhourtodomyhomeworkyesterdayevening.昨天晚上我做作業(yè)用了一個多小時。Itwilltakeusalotofmoneytobuythathouse.買那套房子要花費我們很多錢。做某事花費某人多長時間(錢)[巧學(xué)活用2]——單句語法填空①[2022·新高考卷Ⅰ應(yīng)用文]Itismypleasure________(invite)youtoourEnglishshow“TalkandTalk”whichwillbeconductedat6a．m.thisFriday.②Itisgoodmannersfortheyoung________(give)theirseatstotheold.③Itismyambition________(make)surethatthedisabledpeoplehaveaccesstoallpublicbuildings.④Itisnouse________(argue)withhim,forheissostubborn.toinvitetogivetomakearguing不定式作主語，有時根據(jù)表達的需要，可以在添加疑問代詞或副詞，疑問代詞：who，whom，what，which疑問副詞：when，where，howwhetherE.g.Howtobreakthebadhabitisthequestion.Wheretogohasn'tbeendiscussed.IthasnotbeendecidedwhethertoflytoParis.

3.”疑問詞+todo”作主語

[巧學(xué)活用3]——單句語法填空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.對我們來說，完成這項工作很困難。3.如何控制水污染是一個大問題。4.