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选择性必修三Unit3拔卷选（考试时间：75分钟试卷满分：100分）第一部分阅读理解(共两节，满分50分)第一节（共15小题；每小题2.5分，满分37.5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。AScientistsinMexicosaytheymayhavefoundawaytocuttheproductionofmethane(甲烷),agaslinkedtorisingtemperaturesontheEarth’ssurface.Thescientistssaytheirmethodmayhelpreducethemethanereleasedbycows,oneofthemainproducersofthegas.Whentalkingaboutglobalwarming,manypeoplethinkofcarbondioxide,anotherheat-trappinggas.Methaneisanevenmorepowerfulheat-trappinggas.Cowsareknowntoproducehighlevelsofmethanewhentheyeatandprocessfood.ResearchersattheAutonomousUniversityoftheStateofMexicoarestudyinghowacow'sdietaffectstheproductionofmethane.Theresearchersareusingaspeciallydesignedmachinetomeasuretheeffect.Thescientistsusethemachinetotrytocapturetheanimal'sbreathingtoexaminethemethanereleased.Mostofthegasisreleasedwhencowsbelch.Thedigestivebacteriainacow'sstomachcausestheanimaltosendoutthegasthroughitsmouth.Thereareanestimated1.3to1.5billioncowsintheworld.Eachanimalreleasesasmuchas120kilogramsofmethaneperyear.TheU.S.EnvironmentalProtectionAgencyreportsthat,whenevermeasuredinpounds,theeffectofmethaneonclimatechangeismorethan25timesgreaterthancarbondioxideovera100-yearperiod.Asitisdifficulttocapturethegasreleasedbycowsforuseasenergy,onewaytolessenitsreleaseistochangetheirdiet.Scientistsinsomecountriesarelookingforwaystodecreasecowmethane.Butwhiletheyaretryingdifferentplantsandchemicalcompounds,thoseproductswouldbetoocostlyanddifficulttobringtoMexico.1.Howharmfulisthegassentoffbycows?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.comA.Itismoredifficulttocontrolitsamount.B.Ittakesupmostofhuman-causedmethane.C.Itisthekeyfactortopreventglobewarming.D.Itismoreharmfulthancarbondioxide.2.Whatcanscientistsinsomecountriesdotosettletheproblemcausedbycows?A.Limitthenumberofcows.B.Changewhattheyeat.C.Fixmachinesontheirmouths.D.Usetheirgasesasenergy.3.Whatmaybethebesttitleforthetext?A.WeHadaBetterMethodofRaisingCowsB.CowsAreMuchMoreHarmfulthanCarsC.ResearchersFoundaWaytoReduceMethanefromcowsD.TwoGasesAreCausingtheWarmingofthePlanetBAverageageisrisingaroundtheworld—ademographic(人口统计)changethatmayposeasignificantchallengetoeffortstoslowdownclimatechange.HosseinEstiriatHarvardUniversityandEmilioZaghenioftheMaxPlanckInstituteforDemographicResearch,Germany,havefoundthatenergyuseincreasesaswegetolder,andnotjustbecausewetendtogetwealthier.Anageingpopulationcouldmeanagreaterproportionofsocietywithhigherenergyuse,theirstudysuggests.Theycombinedtwodecades,worthofdatafromthousandsofUShouseholdsandusedthistobuildamodeltorevealhowenergyusevariedacross17agegroupsbetween1987and2009.Theyfoundthat,onaverage,children’senergyconsumptionclimbsastheygrowup,beforedippingslightlywhentheyleavehome.Consumptionthenrisesagainwhenpeoplehittheir30s,beforebrieflydroppingafter55,andthenbeginningtoclimbagain.Thestudyinvolvedfactorssuchasincome,localclimateandtheage,typeandsizeofaperson’shome.Theincreaseinenergyuseatvariouspointsinourlifespan(寿命)seemstobetheresultoflifestyleandhowourneedschangeasweage.Whydoesd...