Unit3语法专项情态动词should与haveto课件外研版八年级英语下册

教学课件外研英语八年级下册

Unit3语法专项——

情态动词should与haveto

全解精讲+分层练习学习目标1.理解情态动词should和haveto的核心含义与本质区别2.掌握should/haveto的肯定、否定形式及基本用法3.能根据语境正确区分并使用should和haveto4.掌握相关句型转换技巧，熟练完成句式改写5.能在填空、选择、改错等题型中灵活运用语法点情态动词的基础概念情态动词用来表达说话人的语气、态度或情感后接动词原形，无人称和数的变化本单元核心：should（主观）和haveto（客观）二者均表“应该/必须”，但使用场景差异显著should核心含义与基本形式核心含义：表建议、劝告、责任或轻微推测，语气委婉肯定形式：should+动词原形否定形式：shouldn't(shouldnot)+动词原形人称特点：所有人称通用，无需根据主语变化should表“建议/劝告”用法+例句这是should最常用的场景，用于给他人提建议、劝诫1.Youshouldtalkwithyourparentsabouttheproblem.2.Sheshouldn'tspendtoomuchtimeonphonegames.3.Weshouldlistencarefullyinclass.4.Youshouldn'tbelateforschooleveryday.should表“责任/义务”用法+例句用于表达分内该做的事，语气比must更温和1.Astudentshouldfinishhishomeworkontime.2.Weshouldprotecttheenvironmentaroundus.3.Ateachershouldcareabouteverystudent.4.Youshouldkeepyourpromisetoyourfriends.should表“推测/预期”用法+例句表示根据情况对事情的发展做出合理推测1.Theyshouldarriveatthestationintenminutes.2.Themovieshouldbeveryinteresting;manypeoplewatchit.3.Heshouldfinishtheworkbytheendofthisweek.4.Thebookshouldbeonthedesk;Iputittherejustnow.haveto核心含义与基本形式核心含义：表客观义务、必要，强调外界规则/要求肯定形式：haveto+动词原形（有人称和数的变化）否定形式：don't/doesn'thaveto+动词原形（表不必）核心：动作不是主观意愿，而是外界迫使必须做haveto人称与数的变化规则第一/二人称单复数（I/you/we/they）：用haveto例：Ihavetogetupearlyeverymorning.第三人称单数（he/she/it/单数名词）：用hasto例：Shehastotakeabustoschool.否定形式：对应变don'thaveto/doesn'thavetohaveto表“客观规则/要求”用法+例句因学校、家庭、社会等规则产生的客观义务1.WehavetowearschooluniformsfromMondaytoFriday.2.Hehastofinishthetrainingbefore6p.m.3.Youhavetofollowthetrafficruleswhencrossingtheroad.4.Theyhavetokeepquietinthelibrary.haveto过去式（hadto）用法+例句表过去发生的客观必要，无人称变化，所有人称通用结构：hadto+动词原形/didn'thaveto+动词原形1.YesterdayIhadtostayathometolookaftermysister.2.Theydidn'thavetogotoschoollastSunday.3.Shehadtotakeataxibecausethebuswaslate.haveto否定式核心含义：不必don't/doesn'thaveto=needn't，表“没有必要做某事”1.Youdon'thavetobringyourtextbook;Iwillsharemine.2.Hedoesn'thavetofinishtheworktoday;it'sduetomorrow.3.Wedon'thavetogetupearlyonweekends.注意：与“禁止”无关，仅表无客观要求should与haveto核心对比表（基础）情态动词核心侧重人称变化否定含义should主观建议、劝告、责任无shouldn't不应该（劝诫）haveto客观规则、外界要求有（hasto/hadto）don'thaveto不必（无要求）should与haveto语境辨析例句对比主观建议（should）Youshouldexerciseeverydaytokeephealthy.YoushouldreadmorebookstoimproveyourEnglish.客观要求（haveto）Youhavetoexerciseforanhouratschooleveryday.Youhavetoreadtwobookseverymonthforyourclass.易混点：don'thaveto与mustn't区别don'thaveto：表“不必”，无客观要求，可做可不做例：Youdon'thavetobringagifttotheparty.mustn't：表“禁止”，绝对不能做，有严格规定例：Youmustn'truninthehallwaysatschool.核心：一个是“无要求”，一个是“严禁止”小练习1——判断用法（should/haveto）判断下列句子该用should还是haveto，标注原因1._________brushyourteethtwiceaday.（_________）2._________wearahelmetwhenyourideabike.（_____________）3._________notplaycomputergamesfortoolong.（_________）4._________finishmyhomeworkbeforewatchingTV.（___________）should表建议haveto表客观规则should表劝诫

haveto表客观要求句型转换1——陈述句变建议句规则：It'sagoodideatodosth.→Youshoulddosth.示例：It'sagoodideatopracticeEnglisheveryday.→YoushouldpracticeEnglisheveryday.关键：保留动词原形，替换句式即可句型转换2——客观必要句改写规则：It'snecessarytodosth.→主语+haveto/hastodosth.示例：It'snecessaryforhertogetupearly.→Shehastogetupearly.关键：根据主语变haveto/hasto句型转换3——无需做某事改写规则：don'tneedtodosth.→don't/doesn'thavetodosth.示例：Youdon'tneedtobuyanewpen.→Youdon'thavetobuyanewpen.关键：主语为三单时，用doesn'thaveto句型转换4——否定劝诫句改写规则：It'snotrighttodosth.→Youshouldn'tdosth.示例：It'snotrighttoshoutatyourparents.→Youshouldn'tshoutatyourparents.关键：直接替换为shouldn't+动词原形句型转换典型例题讲解（1）原句：It'sagoodideaforustojointheEnglishclub.解析：表建议，用should改写，保留动词原形答案：WeshouldjointheEnglishclub.技巧：忽略形式主语it，直接用真实主语作主语句型转换典型例题讲解（2）原句：It'snecessaryforhimtohandinthereporttoday.解析：表客观必要，主语he是三单，用hasto答案：Hehastohandinthereporttoday.技巧：注意第三人称单数的形式变化句型转换典型例题讲解（3）原句：Shedoesn'tneedtogototheofficeonSaturday.解析：表不必，主语she是三单，用doesn'thaveto答案：Shedoesn'thavetogototheofficeonSaturday.技巧：needn't与don't/doesn'thaveto可互换语法易错点提醒（1）1.should后接动词ing形式：错误，必须接动词原形错误：Youshouldreadingmore.正确：Youshouldreadmore.2.haveto的三单形式不变：错误，三单必须用hasto错误：Hehavetogotoschoolearly.正确：Hehastogotoschoolearly.语法易错点提醒（2）3.混淆shouldn't和don'thaveto：前者是“不应该”，后者是“不必”错误：Youdon'thavetoberudetoothers.正确：Youshouldn'tberudetoothers.4.hadto变否定加not：错误，过去式否定用didn'thaveto错误：Hehadnottogoyesterday.正确：Hedidn'thavetogoyesterday.专项习题1——用所给词正确形式填空用should/shouldn't/haveto/hasto/don'thaveto填空1.You___________eattoomuchjunkfood;it'sbadforhealth.2.He___________getupat6a.m.becausehisschoolisfar.3.We___________studyhardforourexams.4.You______________worryaboutme;Icantakecareofmyself.5.They___________followtherulesinthemuseum.shouldn’thastoshoulddon'thavetohaveto专项习题2——句型转换（按要求改写）1.It'sagoodideatotakeawalkafterdinner.（改为should句型）2.It'snecessaryforustocleantheclassroomeveryday.（改为haveto句型）3.Youdon'tneedtowaitformehere.（改为don'thaveto句型）4.It'snotrighttocopyothers'homework.（改为shouldn't句型）5.Sheneedstofinishtheworkbefore5p.m.（改为hasto句型）Youshouldtakeawalkafterdinner.Wehavetocleantheclassroomeveryday.Youdon'thavetowaitformehere.Youshouldn'tcopyothers'homework.Shehastofinishtheworkbefore5p.m.专项习题3——单项选择1.You______drinkmorewaterwhenyouhaveacold.A.shouldB.havetoC.doesn'thavetoD.shouldn't2.He______wearatietowork;it'sthecompanyrule.A.shouldB.hastoC.don'thavetoD.shouldn't3.You______gooutatnight;it'snotsafe.A.shouldB.havetoC.don'thavetoD.shouldn't4.We______takeumbrellas;thesunisshiningbrightly.A.shouldB.havetoC.don'thavetoD.shouldn'tABDC专项习题4——改错（找出错误并改正）1.Youshouldtogotobedearlyeverynight.2.Mymotherhavetogetupearlytomakebreakfast.3.Hedoesn'thastogotoschoolonSaturday.4.Youdon'thavetobelateforthemeetingagain.5.Weshouldplayingsportseverydaytokeepfit.去掉tohave→hashas→havedon'thaveto→shouldn'tplaying→play专项习题5——补全对话（用适当词填空）A:Hi,Tom.Youlookworried.What'swrong?B:Ihaveamathtesttomorrow.I'mnotgoodatmath.A:You____________askyourteacherforhelp.Sheisverykind.B:Iknow,butI'mtooshy.AndI_________finishmymathhomeworkfirst.A:You___________beshy;yourteacherwill