完整word版《新世纪研究生公共英语教材阅读A》课文.docx

完整word版《新世纪研究生公共英语教材阅读A》课文.docx

《完整word版《新世纪研究生公共英语教材阅读A》课文.docx》由会员分享，可在线阅读，更多相关《完整word版《新世纪研究生公共英语教材阅读A》课文.docx（14页珍藏版）》请在冰豆网上搜索。

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。