2020-2021学年潍坊中新双语学校高三英语下学期期末试卷及参考答案第一部分阅读（共两节，满分40分）第一节（共15小题；每小题2分，满分30分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项ABirdmigrationisdescribedastheregular,seasonalmovementofbirdpopulationsfromoneplacetoanotherandbackagain.Thelongerdaysandrichfoodofthenorthernsummerprovidegreaterchancesforbirdstofeedtheiryoung.Thelongerdaylighthoursandenormousfoodresourcesallowbirdstolaylargereggsthanthoseofrelatednon-migratoryspeciesthatremaininthetropicsallyearround.Asthedaysshorteninautumnandthebreedingperiodisover,thebirdsreturntowarmerregionswheretheavailablefoodsupplydifferslittlewiththeseasonschanging.Theadvantagesofmigrationmakeupforthehighstress,physical（消耗）,exertionandotherrisksofthemigration.Daylengthistheprimaryenvironmentalfactorthatencouragesbirdstoprepareformigration.Theyhaveanincreasedappetitewhichresultsinweightgaining,givingthemthefatreservesthatprovideenergyfortheirmigratoryflight.Theyalsoshowmoreactivityatnight,whichiswhenmostbirdsmigrate.Whilethelengthofdayistheprimaryreasonformigration,birdsalsorespondtotemperaturechanges.Forexample,ifaspringislateandthetemperatureislowerthannormal,birdsdelaymigration;ifaspringisearly,birdsalsobeginmigrationearly.Thetimingofthemigratorycyclemustallowbirdstoarriveonthebreedingsitesothatthereistimetobuildabreedingplace,mate,laytheeggs,andhatchtheyoungbeforetherichfoodisavailabletofeedtheyounginthenest.Similarly,ifbirdswaituntiltheclimateintheirnorthernbreedinggroundsbecomestolerable(可忍受的),therewillbenotimetogainthenecessaryweightthatprovidestheenergyneededfortheirsouthboundmigration.1.Whydobirdsmigratetothenorthinspring?AThetemperatureinthesouthhasrisen.B.Theyliketravelingandenjoythejourney.C.Thesummerthereiswarmerthanthatinthesouth.D.Theenvironmentthereismoresuitableforthemtofeedtheirbabybirds.2.Whatarethetwofactorsthatcausebirdstomigrate?A.Daylengthandfoodsupply.B.Nightlengthandhighstress.C.Temperaturechangesanddaylength.D.Foodsupplyandtemperaturechanges.3.Whichcanbethebesttit