完整word版《新世纪研究生公共英语教材阅读A》课文.docx
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完整word版《新世纪研究生公共英语教材阅读A》课文.docx
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完整word版《新世纪研究生公共英语教材阅读A》课文
《新世纪研究生公共英语教材阅读A》课文
Unit3OceanofSand
FromTheGuardian
1.Thereismoredesertsthansunandsand。
Onthesetwopagesyoucanfindouthowplants,animalsandpeoplemanagetosurviveintheseapparentlybarrenplaces。
2.Alldesertsaredry。
Thehot,sandyplaceswethinkofwhenwetalkaboutdesertsaresubtropicaldeserts。
TheyarefoundneartheTropicsofCancerandCapricornwherethewarmairwhichrisesattheEquatorsinksdownagain,givingaclimateofclearskiesandverylowrainfall.TheSaharaisalmostone-thirdthesizeofAfrica,andisnearlyasbigastheU.S.A.,thefourthlargestcountry.Itwasnotalwaysadesert.Overmillionsofyearsithasbeenconveredinice,sea,forestsandgrasslands.
3.Desertwindsareusuallydry.Somedesertsarein“rainshadow”areaswherethewindshavelostwhatmoisturetheyhadcrossinghighground。
Othersareinthemiddleofcontinentswherethewindsblowingoverthemhavelostanymoisturegainedfromdistantoceans.TheGobidesertinMongoliainAsiaisanexampleofsuchaninlanddesert.TheAtacamainnorthernChileisthedriestdesertonEarth。
Partsofthedeserthadnorainfor400years,from1570to1971,andinotherparts,rainshadneverbeenrecordedn.OneofthesandiestdesertsistheTaklaMakan。
Sandstormscanwhipupthesandashighas3,048m(10.000ft)。
WindblownsandintheSaharacanbesofiercethatitwillsandblastthepointoffacaroraeroplane.Thetemperatureatnightinahotdesertcandropbelowfreezing,to-4℃(24℉).Duringtheday,thesandcanbeashotas79℃(175℉)。
Livinginadesertclimate
4.Desertsaredifficultplacesinwhichtolive.Duringthedaytheyareveryhot。
IntheLibyanDesertinNorthAfricathetemperatureon13September1922reached58Cintheshade!
Butdesertnightsareoftencoldbecauseclearskiesallowheattoescapeintotheatmosphere。
Thelackofwatercausedbylowrainfallisbadenough,butrainfallisalsohighlyunpredictable。
Yearsofdroughtcanendintremendousrainstorms。
Manydesertareasarebarerock,orarecoveredwithpebblesandgravel.Sandaccountsforonlyabout15percentoftheearth'sdesertregions.Insomedeserts,thetotalrainfortheyearmightfallinonlytwoorthreestorms.Butthatisenoughforplantseedstosproutandbloom,turningpartsofthedesertintocarpetsofflowersforafewdays。
Howplantssurvive
5.Withinafewhoursofrainfalling,thousandsoffloweringplantswillstarttoappear。
Seedsofplantssuchasthedesertdandelionlieinthegroundforyearswaitingfortherain。
6.Theseplantsdieasthedesertdriesoutagain,leavingtheirseedsforthenextrains。
Otherplantshaveadaptedtotheharshenvironmentbystoringwaterintheirleaves,stemsorroots。
TheAmericansaguarocactuscanhold6to8tonesofwater.Desertplantsoftenhavespreadingrootsystemswhichextracteverydropofmoisturefromtheground.Therootsofthemesquitebushcanbe20mdeep.
7。
Plantsgenerallylosewaterthroughporesintheirleaves.Topreventthis,desertplantshavesmallwaxyleavesandfewerpores。
Manyclosetheirporesduringthedaysotheydonotlosemoisture.Toprotectthemselvesagainstgrazinganimals,someplantshavethornsoranunpleasanttaste。
Cactiareprotectedbytheirsharpspines.CactiarefoundonlyinAmericandeserts.Thetallestaresaguaroswhichcanreach15m(50ft)tall,weigh7tonsandlivefor200years.Waterisstoredinthestemandusedintimesofdrought.
Animallife
8.Althoughdesertsseemempty,fewarewithoutanimals.Mostanimalsshelterfromthedaytimeheatinholesorburrows.Theburrowstrapmoisturearestaycoolerthanthegroundabove。
Inthecoolereveningoratdawn,theanimalsemerge.
9.Smallermammalsoftenhavelargeears.Duringtheday,theanimallosesheatthroughitsears。
Inthedark,largewarntheanimalofunseendangers.
10.Reptilesventuringoutindaytimetrytoavoidtouchingthehotsand。
TheAustralianbeardedlizardsometimesrunsonitshindlegsonly.Theaptlynamedsidewindersnakeonlytouchesthegroundintwoplaces。
11.Alldesertanimalssurviveonlittlewater.Manysmallanimalsliveonthemoistureintheirfood.Largeranimalssuchasthecamelcangowithoutwaterfordays,butdrinkhugeamountswhentheygetthechance.Acamelcandrink10litresofwaterinaminute.
Desertpeoples
12.Overthoughtofyears,peoplehavelearnthowtosurviveinDeserts.TheSanpeopleoftheKalaharidesertinsouthernAfricaandtheAustralianAborigineshuntanimalsandgatherfoodplants。
Theylearntraditionalskillsfromolderpeople.
13.Ontheedgesofthedesert,nomadicpeoplesgrazeflocksofsheepandgoats。
Theyareconstantlymovingtofresherpastures.NomadssuchastheTuaregoftheSaharainNorthAfricawearloosechothingtoprotectthemsandandheat。
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