I can could 表否定的猜测can t couldn tdo现在或将来不可能 e g Hecan t couldn tbeherfather he stooyoung can t couldn tbedoing现在不可能正在 e g Hecan t couldn tbewaitingforusatthestop can t couldn thavedone 过去 不可能 e g Ican t couldn thavelostmykeys Ineverdropthings Shecan thavecaughtthe9 10train forsheonlyleftherhouseat9 15 比较 MayIseethesecretary Try Butshemaynotwanttoseeanyone can could用在疑问句中表猜测e g Can CoulditbeJohn Couldthebankhavemadeamistake e g Thispenlooksmine yetitisn t Whosecan coulditbe 可能 会是谁的呢 Wherecanshehavegone couldhavedone过去能够做某事而没做e g Hewentonfoot buthecouldhavetakenabus e g Iwasfiveminuteslate otherwiseIcouldhavecaughtthetrain Practice Icouldhavefinisheditbetter butI noenoughtime wouldhaveB haveC hadD hadhad ii may might may might表肯定的猜测 语气较弱 may mightdo现在或未来可能发生e g Whyisn tJohninclass Idon tknow Hemay mightbesick Whatareyougoingtodotonight Ihaven tmadeupmymindyet Imay mightgotothelibraryorImay mightjuststayathome may mightbedoing现在可能正在 e g Myfatherisnothere Hemay mightbeworkinginthegarden 将来可能会 e g Theymay mightbewaitingatthestationwhenwearrive may mighthavedone过去可能发生e g Helooksunhappy Hemay mighthavefailedintheexamination mighthavedone过去可能发生某事但未发生e g Youwerestupidtotryclimbingupthere Youmighthavekilledyourself e g Itisagoodthingyoudidn tlendhimthemoney Youmightneverhavegotitback may用于目的 让步状语从句中 表示可以或可能e g Weworkhardthatwemayliveincomfort e g Whatevermayhappen Whateverhappens itdoesn tconcernus iii must must表肯定的猜测mustdo现在一定会e g Hemustknowherphonenumber Hehashadnosleepfor48hours Hemustbeexhausted mustbedong现在一定正在或即将发生e g Itmustberainingnow Hemustbearrivingtonight musthavedone猜测 过去 一定已经发生e g Theymusthaveleft fornobodyisin Youwereontime Youmusthavegotupearlythatmorning musthavebeendoing当时一定正在e g Marywasn tathomewhenwewenttovisither Shemusthavebeenstudyingatthelibrary Notice 反意疑问句Hemustberich Youmusthavehisnumber Theyarenotadmittedtothecinema Hemusthavelosttheirtickets TheymusthavemetJohnonthewayhomeyesterday Iknockedatthedoor butnobodyanswered Hemusthavebeenasleep Atthatmoment nooneansweredmyphone Theymusthavebeenreadinginthestudy isn the don tyou hasn the didn tthey wasn the weren tthey must表主语的固执 偏要 e g Hemustalwayshavehisownway e g Whymustyoubesostubborn e g AsIwassittingdowntosupper thetelephonemustring iv shall should oughtto should表虚拟shouldhavedone oughttohavedone过去应该做某事而没做shouldn thavedone oughtn ttohavedone过去不应该做某事但做了e g Youfailedagain Youshouldhavereviewedyourlessons Butyoudidn t e g Theplantdied Heoughtn ttohavegivenittoomuchwater Buthedid should表猜测 按照常理或常态认为应该如何e g Inmyopinion sheshouldbeelectedbecausesheishonest knowledgeable andcompetent should表万一 用于条件状语从句中e g Ifyoushouldhaveanydifficultywithit ringthisnumber Shouldyouhaveanydifficultywithit ringthisnumber shall用于第一 第三人称 表建议或征求意见 意为 好吗 要不要 e g Shallwegotothemovies Shallhestayhereorleavenow shall用于第二 第三人称 表示说话者的警告 命令 恐吓 允诺 规定等e g Personsunder18shallnotbeemployedinnightwork Youshallgetout v will would will表物的属性 人或动物的习性 e g Woodwillfloat e g Thedoorwillnotopen e g Unlessdrivenbyhunger alionwillnotattackman e g Adrowningmanwillcatchatastraw would 表示过去习惯 行为 习俗 老是 总是 e g Wheneverhehadtime hewoulddosomereading 过去 他一有时间 就会读点书 vi dare 做为情态动词 不用于肯定句 现在时I Hedarenothaveatry Darehehaveatry 过去时I Hedarednothaveatry Daredhehaveatry 做为普通动词 现在时Idaretohaveatry Hedarestohaveatry Idon t Hedoesn tdare to haveatry Doyou Doeshedare to haveatry 过去时I Hedaredtohaveatry I Hedidn tdare to haveatry Didyou Didhedare to haveatry vii need needn thavedone做了过去不必做的事e g Oh therewasplentyoftime Youneedn thavehurried Practice SinceitwasSundayyesterday I towork soIwentfishing needn thavegoneoughtn tgomustn havegonedidn tneedtogo