Unit1Sportsandgamescan和could的用法辨析1)can和could表示能力，can用于现在时，could用于过去时或表示委婉的说法，而beableto可以用于各种时态。【例如】Heisover80butstillcanreadwithoutglasses.HecouldspeakFrench,sohewasabletohelptheFrenchladyyesterday.ThisistheinformationI'vebeenabletogetsofar.Iusedtobeabletorememberthingquickly.2)can和could可以表示可能性和许可。在表示许可时，may比较正式。【例如】Sportsandgamescanbefairlyexpensive.(可能性)Youcanwalkformilesinthecountrywithoutmeetinganyone.(可能性)Youcangonowifyoureallyhavesomethingurgent.(许可)YoumayreturnthebooksyouborrowedtothelibraryonFriday.(许可)3)can和could接动词的完成形式，表示可能已经做某事。can用在否定和疑问句中，表示不相信、怀疑等态度。【例如】Theycan'thavegoneoutbecausethelightison.Hecan'tbeinthelibrary,forIsawhiminthedepartmentstoreamomentago.You____herintheofficelastFriday;shehasbeenoutoftownfortwoweeks.A)needn'thaveseenB)musthaveseenC)mighthaveseenD)can'thaveseen本句译为：你上星期五不可能在办公室看到她。她已经离开镇上两个月了。can'thaveseen意思是：不可能干什么，含不相信的态度，与句意相符，故选择D.
