shall,shouldoughttoneeddar情态动词定义:表示说话人的情绪、态度或语气的动词叫情态动词。情态动词语法特征1）情态动词不能单独作谓语，没有人称，数的变化，即情态动词第三人称单数不加-s。2）情态动词的否定式是在情态动词后面直接 +not 。3）情态动词的疑问式是把情态动词提到主语前。主要情态动词can,could（beableto）may,mightmust（haveto）will,would情态动词的用法I.can/could1. ___Can___youspeakJapanese?Justalittle.2. Onlythejudge___can___saveherfromprison.3. I___could___driveacarbeforeIleftmiddleschool.4. ItwassodarkthatI___could___seenothing.Note: 表能力、有权力 （ could 是 can 的过去式） 5. --Can/CouldIgohomenow?--Yes,youcan.—No,youcan't.6. --___Can/Could___IspeaktoAndrew?7. You___can't___（not）smokehere.Note: （口语）允许、请求，表可以 （ could 非 can 的过去式，表委婉 ） 8. It___can___/couldbeverycoldhere,eveninspring.9. Sheisclever,butshe___can___/could___bedullsometimes.Note: （表示偶然现象发生的可能性）有时会，时而可能 10. It___can't___/couldn't___（not）bemyfather.Heisabroadnow.11. Thereissomeoneoutside.Who___can___itbe?12. You__can't/couldn'thaveseenhim__（notsee）him.Hewasnotthere.13. She__can't/couldn'thavebeen___（notbe）morethansixthen.14.He__can't/couldn'thavefinished___(notfinish)theworklastnightwithoutyourhelp.Note: 表推测 ( 否定、疑问句 ) 15. He__couldhavetold__(tell)metheanswerbutherefusedto.ModalVerbsNote: 过去本能做而没有做 16. You_cannot/canneverdotheworktoowell.17. You_cannot/cannever__becarefulenoughinyourstudy.Note:cannot...too;cannever ・・・ too;cannotenough 再 … 都不为过；越 … 越好 can&beableto区别：1・can 只有两种时态现在时 can&过去时 couldbeableto 有各种时态2・用于一般所具有的能力，可以互换，但是当表示成功做到时，通常用beableto 或 manageto1. He_can/isableto_writemusic.2. Weshall__beableto__finishtheworksoon.3. Ihaven't_beenableto_findthebook.4. He_could/wasableto__swimlikeafishwhenhewasyoung.5. ItalkedwithherforalongtimeandfinallyI__wasableto_makeherbelieveme.6. Thefirespreadthroughthebui...
