情态动词表推测的用法

的用法should表示推测时,表示按常规、常理的推测,即“(正常情况下)按理应该”例如:①It’snearlyseveno’clock.Jackshouldbehereatanymoment.②Threeweeksshouldbeenough.③Thereshouldn’tbeanydifficultyaboutpassingthedrivingtestsinceyouhavepracticedalotinthedrivingschool.注:表推测时might不是may的过去式,could不是can的过去式,所以might/could+v不表示对过去的推测,而是表示might/could比may/can推测的可能性小.五、情态动词+havedone表示“原本...而未...”的情态动词有could/might/should/oughtto/would等.1.couldhavedone表示本来能做某事而实际没有做Hecouldhavepassedtheexam,buthewastoocareless.2.mighthavedone表示本可能做某事而实际没有做Itwasreallydangerous。Imighthavekilledmyself.pletedtheworkearlier.3.shouldhavedone表示本应该做某事而实际没有做=om,youaretoolazy.Theworkshouldhavebeenfinished.Yououghttohavebeenherefiveminutesago.4.wouldhavedone虚拟语气,表示对过去事实相反的假设Iwouldhavetoldyouallabouttheboy’sstory.Butyoudidn’taskme.Withoutyourhelp,Iwouldn’thavefinishedthework.