比较need和dare这两词既可做实义动词用，又可做情态动词用。作为情态动词，两者都只能用于疑问句，否定句和条件句。need作实义动词时后面的不定式必须带to，而dare作实义动词用时,后面的to时常可以被省略。1)实义动词：need（需要,要求）need+n./todosth2)情态动词：need，只用原形need后加do，否定形式为neednot。Needyougoyet?Yes,Imust./No,Ineedn't.3)need的被动含义：need,want,require,worth（形容词）后面接doing也可以表示被动：needdoing=needtobedone带to的情态动词带to的情态动词有四个：oughtto,haveto,usedto,beto,如加上havegotto,(=must),beableto，为六个。它们的疑问，否定形式应予以注意：Dotheyhavetopaytheirbillbeforetheendofthemonth?Shedidn'tusetoplaytennisbeforeshewasfourteen.Yououghtnottohavetoldherallaboutit.Oughthetoseeaheartspecialistatonce.?oughtto本身作为情态动词使用。其他的词作为实义动词使用，变疑问，否定时，须有do等助动词协助。典型例题Tomoughtnotto___meyoursecret,buthemeantnoharm.A.havetoldB.tellC.betellingD.havingtold答案A。由于后句为过去时，告诉秘密的动作又发生在其前因，此地应用过去完成时，但它在情态动词oughtto后，所以用have。情态动词的回答方式问句肯定回答否定回答Needyou…?Yes,Imust.No,Ineedn'tMustyou…?/don'thaveto.典型例题1）---CouldIborrowyourdictionary?---Yes,ofcourse,you____.A.mightB.willC.canD.should答案C.could表示委婉的语气，并不为时态。答语中ofcourse，表示肯定的语气，允许某人做某事时，用can和may来表达，不能用could或might。复习：will与you连用，用来提出要求或下命令。should与you连用，用来提出劝告。2）---ShallItellJohnaboutit?---No,you___.I'vetoldhimalready.A.needn'tB.wouldn'tC.mustn'tD.shouldn't答案A。needn't不必，不用。wouldn't将不,不会的。mustn't禁止、不能。shouldn't不应该。本题为不需要，不必的意思，应用needn't。3）---Don'tforgettocometomybirthdaypartytomorrow.---______.A.Idon'tB.Iwon'tC.Ican'tD.Ihaven't答案B.will既可当作情态动词，表请求、建议、也可作为实义动词表"意愿、意志、决心"，本题表示决心，选B。will和would注意：1）wouldlike；Wouldliketodo=wantto想要，为固定搭配。Wouldyouliketogowithme?2）Willyou…?Wouldyoulike…?表示肯定含义的请求劝说时，疑问句中一般用some,而不是any。Wouldyoulikesomecake?3）否定结构中用will，一般不用would,won'tyou是一种委婉语气。Won'tyousitdown?wouldrather表示"宁愿"wouldratherdowouldrathernotdowouldrather…than…宁愿……而不愿。还有wouldsooner,hadrather,hadsooner都表示"宁愿"、"宁可"的意思。IfIhaveachoice,Ihadsoonernotcontinuemystudiesatthisschool.Iwouldratherstayherethangohome.=Iwouldstayhereratherthangohome.典型例题----Shallwegoskatingorstayathome?----Which___do?A.doyouratherB.wouldyouratherC.willyouratherD.shouldyourather答案B。本题考查情态动词rather的用法，wouldrather+dosth意为"宁愿"，本题为疑问句，would提前，所以选B。hadbetter表示"最好"hadbetter相当于一个助动词，它只有一种形式，它后面要跟动词原形。hadbetterdosthhadbetternotdosthItisprettycold.You'dbetterputonmycoat.She'dbetternotplaywiththedog.hadbetterhavedonesth表示与事实相反的结果，意为"本来最好"。Youhadbetterhavecomeearlier.
