大学英语B级辅导—词汇与结构重要语法项目：主谓一致；形容词和副词的比较级和最高级；人称代词；情态动词；冠词和介词；不定式，动名词搭配；固定句型；词义辨析；时态和被动语态；定语从句；倒装；虚拟语气（划线部分为考试频率较高项目）情态动词的用法1）.can:能，会表示能力，相当于beableto。2）.may:可以，可能，或许3）.must:必须，表示肯定的猜测，mustbe准是，一定是4）.could:比can语气更委婉，客气，并不表示过去时。5）.注意回答形式：⑴MayI...?Yes,youmay.No,youcan't(mustn't).⑵MustI...?Yes,youmust.No,youneedn't.6）.must表示说话人的主观看法，haveto表示外界客观愿望,不得不。如:⑴Hermotherisill.Shehastostayathomeandtakecareofher.⑵Youmustlookafteryourclothes.7）.should表示"应当，应该"，与疑问词连用表意外，惊奇。WhatshouldIdo?我该怎么办呢？8）.will,would在交际用语中，would更客气，表邀请。9）.hadbetter表示"最好"，相当于一个助动词，它只有一种形式，它后面要跟动词原形。例如：Itisprettycold.You'dbetterputonmycoat.天相当冷。你最好穿上我的外套。She'dbetternotplaywiththedog.她最好不要玩耍那条狗。10).wouldrather表示"宁愿"wouldratherdowouldrathernotdowouldrather…than…宁愿…而不愿。Iwouldratherstayherethangohome.=Iwouldstayhereratherthangohome.我宁愿呆在这儿，而不愿回家。11）情态动词+have+过去分词1)may(might)have+donesth,can(could)have+donesth表示过去，推测过去时间里可能发生的事情。Philipmay(might)havebeenhurtseriouslyinthecaraccident.Philipcan(could)havebeenhurtseriouslyinthecaraccident.2)musthave+donesth，对过去时间里可能发生的事情的推测，语气较强，具有"肯定"，"谅必"的意思。---Lindahasgonetowork,butherbicycleisstillhere.---Shemusthavegonebybus.否定推测用can't。例如：IfTomdidn'tleavehereuntilfiveo'clock,hecan'tbehomeyet.如果汤姆五点才离开这儿，他此时一定还未到家。3)oughttohavedonesth,/shouldhavedonesth本应该做某事，而事实上并没有做。否定句表示"不该做某事而做了"。Yououghtto(should)havebeenmorecarefulinthisexperiment.Heoughtnottohavethrowntheoldclothesaway.（事实上已扔了。）oughtto在语气上比should要强。4)needn'thavedonesth本没必要做某事Idressedverywarmlyforthetrip,butIneedn'thavedoneso.Theweatherwashot.5)wouldliketohavedonesth本打算做某事Iwouldliketohavereadthearticle,butIwasverybusythen.真题操练：1.Ibelievedhiswife____forhimjustasIwasprayingforJames.A.shouldbeprayingB.mustbeprayingC.wouldbeprayingD.mustpray2、Mywalletisnowheretobefound.I________inthestore.A：mustdropitB：musthavedroppeditC：shouldhavedroppeditD：oughttohavedroppedit3.Acomputer_________thinkforitself,itmustbetoldwhattodo.A.can’tB.couldn’tC.maynotD.mightnot4.Id