小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com必修第二册UNIT5HUMANSANDNATURE(二)Ⅰ.阅读理解A(★)Asashiftinthepolarvortex(极地涡旋)sweptacrossmuchoftheUS，manypeopleinthecountrywerehitwithasuddensnapofcold.Heavyiceandsnowcoupledwithfallentreescausedtheoutagesinmajorcities，withcompaniesunabletotelltheircustomerswhenpowerwillberestored.Polarvorticeswerenoticedlongago.Butthefirstknownuseoftheterm“polarvortex”wasinamagazinein1853.Polarvorticesarepresentyear-round，butwedon’thearaboutthemuntiltheycauseproblems.TheymaintainfreezingtemperaturesattheNorthandSouthPolesbymovingintightcounterclockwisepatterns.Polarvorticesgrowstrongerinwinterandweakeninsummer.Theyarekeptinplaceatthepolesbyanotheratmosphericcurrentcalledthejetstream.However，whenthejetstreamsweaken，thecoldwindsofthepolarvortexarepushedsouthwardsanditisduringthistimethatpeoplebegintopayattention!InTexas，roadsfrozeover，causingsixtrafficdeaths，andmanyschoolswereshutdown.PeoplearenottheonlyEarthlingstostrugglewiththecold.Cropsandanimalsarealsofreezing.Thiscouldhavemajorconsequences，especiallyifherdsofcattledie.Ifsnowblockscattle，theanimalscan’treachbasicnecessitieslikefoodandfreshwater.Onabrighternote，someTexascitiesweremorepreparedthanothers，forinstance，Amarillo，whichislocatedinNorthTexas，sotheyaremoreaccustomedtocoldertemperatures.Amarilloisnotablebecausethecitywasredesignedtostanduptoseverewinterstorms.Officialshavespreadoutfirestationstoincreasecoverageoffirstresponders，employedmodifieddumptrucksforclearingice，andupgradedciviccenterstoprovideshelterduringstorms.Hopefully，otherTexascitieswillfollowthegoodexamplesetbyAmarillo!1．Whatdoestheunderlinedword“outages”refertoinparagraph1?A．Trafficjams.B．Powerstruggles.C．Powercuts.D．Trafficaccidents.2．Whatcanwelearnaboutpolarvortices?A．Theygrowstrongerinsummer.B．Theyareaffectedbyjetstreams.C．Theywerefirstobservedin1853.D．Theymoveinaclockwisedirection.3．Whatisthelastbutoneparagraphmainlyabout?A．Thedefinitionofthepolarvortex.B．Thecharacteristicsofthepolarvortex.小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.comC．Thewaystodealwiththepolarvortex.D．Theseriousimpactmadebythepolarvortex.4．WhyisAmarillostriking?A．BecauseitislocatedinthenorthofTexas.B．Becauseithasbeenupgradedandmodernized.C．Becauseithasbeenregardedasanexampletoothercities.D．Becauseithastakeneffectivemeasurestoresistwinterstorms.BAnewstudyanalyzingstonetoolsfromsouthernChinaprovidestheearliestevidenceofriceharvesting，datingtoasearlyas10,000yearsago.Theresearchersidentifiedtwomethodsofharvestingrice，whichhelpedstartricedomestication.Toharvestrice，somesortoftoolswouldhavebeenneeded.“Forquitealongtime，oneofthepuzzleshasbeenthatharvestingtoolshavenotbeenfoundinsouthernChinafromtheearlyNeolithicperiodorNewStoneAge(10,000－7,000BeforePresent)—thetimeperiodwhenweknowricebegantobedomesticated，”saysleadauthorJiajingWang，anassistantprofessorofanthropologyatDartmouth.“However，whenarchaeologists(考古学家)wereworkingatseveralearlyNeolithicsitesintheLowerYangtzeRiverValley，theyfoundalotofsmallpiecesofstone，whichhadsharpedgesthatcouldhavebeenusedforharvestingplants.”“Maybesomeofthosesmallstonep...