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时间:2020-03-15
《2016职称英语考试复习理工类阅读判断试题.doc》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、2016职称英语考试复习理工类阅读判断试题 Onlyspecialplantscansurvivetheterribleclimateofadesert,fortheseareregionswheretheannualrangeofthesoiltemperaturecanbeover75℃.Furthermore,duringthesummertherearefewcloudsintheskytoprotectplantsfromthesun'sray.Anotherproblemisthefactthattherearefrequentlystrongwindswhich
2、drivesmall,sharpparticlesofsandintotheplants,tearinganddamagingthem.Themostdifficultproblemforallformsofplantlife,however,isthefactthattheentireannualrainfalloccursduringafewdaysorweeksinspring. Grassesandflowersindesertsurvivefromoneyeartothenextbyexistingthroughthelong,hot,dryseasoninthef
3、ormofseeds.Theseseedsremaininactiveunlesstherightamountofrainfalls.Ifnorainfalls,orifinsufficientrainfalls,theywaituntilthenextyear,orevenstillthenext.Anotherfactorthathelpstheseplantstosurviveisthefactthattheirlifecyclesareshort.Bythetimethatthewaterfromthespringrainsdisappears——justafewwee
4、ksafteritfalls——suchplantsnolongerneedany. Theperennialshavespecialfeatureswhichenablethemtosurviveasplantsforseveralyears.Thus,nearlyalldesertperennialshaveextensiverootsystemsbelowgroundandasmallshootsystemaboveground.Thelargerootnetworkenablestheplanttoabsorbasmuchwateraspossibleinashort
5、time.Thesmallshootsystem,ontheotherhand,considerablylimitswaterlossbyevaporation. Anotherfeatureofmanydesertperennialsisthataftertherainyseasontheylosetheirleavesinpreparationforthelong,dryseason,justastreesinwetterclimateslosetheirsinpreparationforthewinter.Thisreducestheirwaterlossbyevapo
6、rationduringthedryseason.Then,innextrainyseason,theycomefullyaliveoncemore,andgrownewbranches,leavesandflowers,justasthegrassesandflowersindesertdo. 16.Ordinaryplantsareunabletosurviveinthedesertmainlybecauseofthechangeableweather. A.Right B.Wrong C.Notmentioned 17.Grassesandflowersinde
7、sertareabletosurvivebecausetheystayintheformofseedstowaitfortherightamountofwatertocome. A.Right B.Wrong C.Notmentioned 18.Grassesandflowersinthedesertwhoselifecyclesareshortshowstheirabilitytoadapttothequickdisappearanceofrainwaterthereafterit
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