江苏上冈实验初级中学胡荣艳
情态动词是一种本身有一定的词义,但要与动词原形及其被动语态一起使用,给谓语动词增添情感色彩,表示说话人对有关行为或事物的态度和看法,认为其可能、应该或必要等。情态动词有can(could),may(might),must,haveto,shall(should),will(would),dare(dared),need(needed),oughtto等,后面跟原形动词,无人称和数的变化。
一、can,could
(1)表示能力(体力、知识、技能)。如:
Canyoucarrythisheavybag?(体力)
MarycanspeakFrench.(知识)
Canyouswim?(技能)
此时可用beableto代替。can只有一般现在时和一般过去式,而beableto则有更多的时态。如:
I’llnotbeabletogotherethisafternoon.
当表示“经过努力才得以做成功某事”时应用beableto,不能用can。如:
Hewasabletogotothepartyyesterdayeveninginspiteoftheheavyrain.
(2)表示请求和允许。如:
—CanIleavenow?
—Yes,youcan./No,youcan’t.
此时可与may互换。在疑问句中还可用could,might代替,不是过去式,只是语气更委婉,不能用于肯定句和答语中。如:
—CouldIcometoseeyoutomorrow?
—Yes,youcan.(No,I’mafraidnot.)
(3)表示客观可能性(客观原因形成的能力)。如:
They’vechangedthetimetable,sowecangobybikeinstead.
Thisroomcanhold500peopleatleast.
(4)表示推测(惊讶、怀疑、不相信的态度),用于疑问句、否定句和感叹句中。如:
Canthisbetrue?
Thiscan’tbedonebyher.
Howcanthisbetrue?
二、may,might
(1)表示请求和允许。might比may语气更委婉,而不是过去式。否定回答时可用can’t或mustn’t,表示“不可以,禁止”。如:
—Might/MayIdanceinthisroom?
—No,youmustn’t.
—May/MightItakethismagazineoutoftheroom?
—Yes,youcan.(No,youcan’t/mustn’t.)
用MayI...?征徇对方许可时比较正式和客气,而用CanI...?在口语中更常见。
(2)用于祈使句,表示祝愿。如:
Mayyousucceed!
(3)表示推测、可能性(不用于疑问句)。might不是过去式,它所表示的可能性比may小。如:
Hemay/mightbeverybusynow.
Yourmothermay/mightnotknowthefact.
三、must,haveto
(1)表示必须、必要。如:
Youmustcomeontime.
在回答引出的问句时,如果是否定的,不能用mustn’t(禁止,不准),而用needn’t,don’thaveto(不必)如:
—Mustwehandinourexercisebookstoday?
—Yes,youmust.
—No,youdon’thaveto/youneedn’t.
(2)must是说话人的主观看法,而haveto则强调客观需要。must只有一般现在时,haveto有更多的时态形式。如:
Theplayisn’tinteresting,Ireallymustgonow.
IhadtoworkwhenIwasyourage.
(3)表示推测、可能性(只用于肯定的陈述句)。如:
You’reTom’sgoodfriend,soyoumustknowwhathelikesbest.
Yourmothermustbewaitingforyounow.
四、dare,need
(1)dare作情态动词用时,常用于疑问句、否定句和条件从句中,过去式为dared。如:
HowdareyousayI’munfair?
Hedaren’tspeakEnglishbeforesuchacrowd,darehe?
Ifwedarednotgotherethatday,wecouldn’tgetthebeautifulflowers.
(2)need作情态动词用时,常用于疑问句、否定句。在肯定句中一般用must,haveto,oughtto,should代替。如:
Youneedn’tcomesoearly.
—NeedIfinishtheworktoday?
—Yes,youmust./No,youneedn’t.
(3)dare和need作实义动词用时,有人称、时态和数的变化。在肯定句中,dare后面常接带to的不定式。在疑问句和否定句中,dare后面可接带to或不带to的不定式。而need后面只能接带to的不定式。如:
Idaretoswimacrossthisriver.
Hedoesn’tdare(to)answer.
Heneedstofinishhishomeworktoday.
五、shall,should
(1)shall用于第一人称,征求对方的意见。如:
Whatshallwedothisevening?
(2)shall用于第二、三人称,表示说话人给对方的命令、警告、允诺或威胁。如:
Youshallfailifyoudon’tworkhard.(警告)
HeshallhavethebookwhenIfinishit.(允诺)
Heshallbepunished.(威胁)
六、will,would
(1)表示请求、建议等,would更委婉。如:
Will/Wouldyoupassmetheball,please?
(2)表示意志、愿望和决心。如:
Iwillneverdothatagain.
Theyaskedhimifhewouldgoabroad.
(3)would表示过去反复发生的动作或某种倾向。would表示过去习惯时比usedto正式,且没有“现已无此习惯”的含义。如:
Duringthevacation,hewouldvisitmeeveryotherday.
Thewoundwouldnotheal.
(2)表示估计和猜想。如:
Itwouldbeaboutteno’clockwhenshelefthome.
七、should,oughtto
(1)should,oughtto表示“应该”,oughtto表示义务或责任,比should语气重。如:
Ishouldhelpherbecausesheisintrouble.
Yououghttotakecareofthebaby.
(2)表示劝告、建议和命令。should,oughtto可通用,但在疑问句中常用should。如:
Youshould/oughttogotoclassrightaway.
ShouldIopenthewindow?
(3)表示推测,should,oughtto表客观推测,must表主观推测。如:
Hemustbehomebynow.(断定他已到家)
Heoughtto/shouldbeathomebynow.(不太肯定)
Thisiswheretheoilmustbe.(直爽)
Thisiswheretheoiloughtto/shouldbe.(含蓄)