【英语】四川省雅安市天全中学2015-2016学年高二上学期第11周周练

《【英语】四川省雅安市天全中学2015-2016学年高二上学期第11周周练》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、天全中学2015—2016学年上期高二第11周周考英语试题（满分100分时间35分钟）班级：姓名：成绩：第一节：阅读理解（4*2.5=10分）ArecentstudyofancientandmodernelephantshascomeupwiththeunexpectedconclusionthattheAfricanelephantisdividedintotwodistinct(不同的)species.ThediscoverywasmadebyresearchersatYorkandHarvardUniversitieswhentheywereexam

2、iningthegeneticrelationshipbetweentheancientwoollymammothandmastodontomodernelephants—theAsianelephant,Africanforestelephant,andAfricansavannaelephant.OncetheyobtainedDNAsequences(序列)fromtwofossils(化石),mammothsandmastodons,theteamcomparedthemwithDNAfrommodernelephants.Theyfoundtot

3、heiramazementthatmodernforestandsavannaelephantsareasdistinctfromeachotherasAsianelephantsandmammoths.ThescientistsuseddetailedgeneticanalysistoprovethattheAfricansavannaelephantandtheAfricanforestelephanthavebeendistinctspeciesforseveralmillionyears.Thedivergenceofthetwospeciesto

4、okplacearoundthetimeofthedivergenceofAsianelephantsandwoollymammoths.Thisresultamazedallthescientists.Therehaslongbeendebateinthescientificcommunitythatthetwomightbeseparatespecies,butthisisthemostconvincingscientificevidencesofarthattheyareindeeddifferentspecies.Previously,manyna

5、turalistsbelievedthatAfricansavannaelephantsandAfricanforestelephantsweretwopopulationsofthesamespecies,despitetheelephants'significantsizedifferences.Thesavannaelephanthasanaverageshoulderheightof3.5metreswhiletheforestelephanthasanaverageshoulderheightof2.5metres.Thesavannaeleph

6、antweighsbetweensixandseventons,roughlydoubletheweightoftheforestelephant.Butthefactthattheylooksodifferentdoesnotnecessarilymean8theyaredifferentspecies.HowevertheprooflayintheanalysisoftheDNA.AlfredRoca,assistantprofessorintheDepartmentofAnimalSciencesattheUniversityofIllinois,s

7、aid,“Wenowhavetotreattheforestandsavannaelephantsastwodifferentunitsforconservationpurposes.Since1950,allAfricanelephantshavebeenconservedasonespecies.Nowthatweknowtheforestandsavannaelephantsaretwoverydistinctiveanimals,theforestelephantshouldbecomeabiggerpriority(优先)forconservat

8、ionpurposes.”1．Oneofthefossilsstu