情态动词讲解

情态动词一、情态动词的含义1.Theboycouldspeakthreelanguageswhenhewas12.2.MayIhaveyourname?3.Shallwebeginnow?4.Youmustobeytheschoolrules.1.含义：表示说话人的情绪、态度或语气的动词2.特点：情态动词不能单独作谓语，需要与另外一个动词一起作谓语eg.Hecanplaybasketballwell.3.否定式在情态动词后直接加noteg.maynotcan和could的用法关于“can"的句子1.表“能力”Somedogscansmelloutdrugs(毒品).一些狗能够嗅出毒品。2.表“许可”CanIuseyouriphone?3.表示“推测”，用于否定句中表示“不可能”Youcan'tbetired.Youhaveonlybeenworkingforanhour.你不可能累，你仅仅工作了一个小时。4.表示客观的可能性，意为"有时可能会"Everyonecanmakemistakesinhislife.5.表示“惊讶”“怀疑”态度Howcanyoubesocareless?could1.表示can的过去式Hecanspeakthreelanguages.Hecouldspeakthreelanguageswhenhewasthreeyearsold.2.表示现在的“能力和许可”，语气比can委婉CouldＩcometoseeyoutomorrow?Yes,youcan.(答语只能用can)/No,I'mafraidnot.can的习惯用法1.can'thelpdoingsth忍不住；不禁我情不自禁的笑了起来。Ican'thelplaughing.2.can't(help)butdo只好做某事;不得不Ican'thelpbutwaitforher.3.can't.....too....再....也不为过Youcan'tbetoocarefulwhendriving.开车时你再小心也不为过。havedone结构1.can/couldhavedone或can't/couldn'thavedone表示对过去事情的推测Youcouldn'thaveseenhimlastnight.Isawhimoffattheairport.2.couldhavedone表示对过去的虚拟，意为本能够做某事Youcouldhavedonebetter,butyoudidn'ttryyourbest.May和might的用法1.表示征求意见或请求许可MayＩuseyourcar?Yes,youcan.might更加委婉2.表“可能”Theroadmay/mightbelocked.a.might表示过去的可能b.might表示现在的可能，比may的可能性小3.may位于句首表示祝愿Mayyoubehappy!Mayyousucceed!4.习惯用法May/mightaswelldosth(最好，不妨）我最好还是去。Imightaswellgo.5.havedone结构a.may/mighthavedone表示对过去事情的推测Nobodyansweredthedoor.Theymighthavefallenasleep.b.mighthavedonesth表虚拟，意为“本来可以”Youmighthavegivenhimmorehelp.must的用法1.表“必须”Plantsmusthavewaterinordertolive.植物必须有水才能活。must主观haveto客观2.表“推测”，意为“准是，一定”a.must+v对现在情况的推测Hemustbedad.他准是疯了。b.must+be+ving对将来或现在进行时的推测Itmustberainingtomorrow.明天一定胡下雨。c.musthavedonesth对过去事情的推测Shedidn'tcometoschool.Shemusthavebeenill.3.must用于疑问句中，表示责备或抱怨，译为“偏要或非得”Mustwehandinourhomeworktoday?Yes,youmust.4.mustn't意为“禁止”Carsmustn'tbeparkedhere.will的用法1.will用于第二人称的疑问句表示征求意见2.will/would表示个人意愿,意为“要；愿”3.will/would表示“习惯性，经常性”，意为“总是，老是”4.will/would表示事物的功能或倾向性，意为“能，行”Iwilldomybesttohelpyou.Whenhewasthere,hewouldgotothatcoffeeshopafterworkeveryday.Thedoorwon'topen.Wouldyouacceptthisinvitation?征求意见时would较will委婉客气个人意愿某种习惯，经常性事物的功能征求意见5.wouldhavedone表示对过去的虚拟，意为本来可以Johndidn'tworkhardathislesson,otherwisehewouldhavepasssedtheexam.shall的用法1、用于第一、第三人称的疑问句，表示征求意见Shallwebeginourclass?Shallhecometoseeyou?2、用于第二、第三人称的陈述句，表示命令、威胁、警告或承诺Sheshallstudy,orsheshallleavethecollege.HeshallhavethebookwhenIfinishreading.警告承诺3.shall表示法律条文和规章制度中的要求意为（按照规定）必须，应该Personsunder18shan'tbeemployedinwork.should的用法1、表示责任、义务、劝告、建议，意为"应该"Studntsshouldrespectteachers.Theyshouldbereadyby12:00.2.在肯定句中表示推测，意为“按理应该”Itshouldbeafinedaytomorrow.It's4o'clock.TheyshouldbeinNewYorknow.(可能性比must小）3.表示惊讶、赞叹或不满情绪，意为“竟然会”Ican'timaginethatsuchawell-dressedmanshouldbesorude.4.should/shouldn'thavedonesth，对过去的虚拟意为“本应该、本不应该Theyshouldhavefinishedtheirhomework.need的用法1.need在肯定句中多用于实义动词Heneedstofinishitthisevening.2.做情态动词多用于否定句、疑问句、条件句Ineedn'tuseaclocktowakemeupbecauseatsixo'clockeachmorningthetrain