《新世纪研究生公共英语教材阅读A》课文.docx

《新世纪研究生公共英语教材阅读A》课文.docx

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《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,thesandcanbeashotas

79℃（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,someplantshavethornsoranunpleasant

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taste.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.Tuaregmenprotecttheirfaceswithaveil.

14.Insomedeserts,oases（fertileareas）formaroundwellsorsprings.Aroundoasestherearesettlementsandsomethingfarms.Themud-brickhousesarekeptcoolbytheirthickwindowlesswalls.

Onthemove

15.Desertsarespreading.Already12percentoftheworld‘slandisdesert,andeveryyearanother12millionhectaresbecomeuselessforfarming.Asthefollowingshows，desertificationhasmanycauses.Theendresultisthatthesoilbecomesexposedandiseasilyeroded.

16.Throughouttheworld，governmentsandaidagenciestrytopreventdesertification.Therearenosimpleanswers,butsuccessfulprojectshavehelpedpeopleinpoorercountriestohelpthemselves.Theschemesuseknowledgeandresourcesthatarereadilyavailabletolocalcommunities.Theyinclude:

plantingtreesandhedgestoprotectcropsfromgrazinganimalsandwinderosion.Insomeareas，peoplehavebuiltlinesofstonesacrossslopestopreventrainwaterrunningawayandtoallowittosoakintothesoil.

Unit4ThreeKindsofFatigue

Fatigueisoneofthemostcommoncomplaintsbroughttodoctors,friends,andrelatives.You'dthinkinthiseraoflabor-savingdevicesandconvenienttransportationthatfewpeoplewouldhavereasontobesotired.Butprobablymorepeoplecomplainoffatiguetodaythaninthedayswhenhaywasbaledbyhandandlaundryscrubbedonawashboard.

Thecausesofmodern-dayfatiguearediverseandonlyrarelyrelatedtoexcessivephysicalexertion.Therelativelyfewpeoplewhodoheavylaboralldaylongalmostnevercomplainabout

beingtired,perhapsbecausetheyexpecttobe.Today,physiciansreport,tirednessismorelikelyaconsequenceofunder-exertionthanofwearingyourselfdownwithover-activity.Infact,increasedphysicalactivityisoftenprescribedasacureforloweringenergy.

Physical.Thisisthewell-knownresultofoverworkingyourmusclestothepointwhere

metabolicwasteproducts—carbondioxideandlacticacid—accumulateinourbloodandreduceyourstrength.Yourmusclescan'tcontinuetoworkefficientlyinabathofthesechemicals.Physicalfatigueisusuallyapleasanttiredness,suchasthatwhichyoumightexperienceafter

playingahardsetoftennis,choppingwood,orclimbingamountain.Thecureissimpleandfast:

Yourest,givingyourbodyachancetogetridofaccumulatedwastesandrestoremusclefuel.

Pathological.Herefatigueisawarningsignorconsequenceofsomeunderlyingphysicaldisorder,perhapsthecommoncoldorfluorsomethingmoreseriouslikediabetesorcancer.Usuallyothersymptomsbesidesfatiguearepresentthatsuggestthetruecause.

Evenafteranillnesshaspassed,you'relikelytofeeldraggedoutforaweekormore.Takeyourfatigueasasignaltogoslowwhileyourbodyhasachancetorecoverfullyevenifallyouhadwasacold.Pushingyourselftoresumefullactivitytoosooncouldleadtoarelapse（旧病复发）andalmostcertainlywillprolongourperiodoffatigue.

Eventhoughillnessisnotfrequentcauseofprolongedfatigue,it'sveryimportantthatitnotbeoverlooked.Therefore,anyonewhofeelsdrainedofenergyforweeksonendshouldhaveathoroughphysicalcheck-up.Butevenifnothingshowsupasaresultofthevariousmedicaltests,thatdoesn'tmeanthere'snothingwrongwithyou.

Psychological.Emotionalproblemsandconflicts,especiallydepressionandanxiety,arebyfarthemostcommoncausesofprolongedfatigue.Fatiguemayrepresentadefencemechanismthatpreventsyoufromhavingtofacethetruecauseofyourdepression,suchasthefactthatyouhateyourjob.Itisalsoyourbody'ssafetymechanismforexpressingrepressedemotionalconflicts,suchasfeelingtrappedinanungratefulroleoranunhappymarriage.Whensuchfeelingsarenotexpressedopenly,theyoftencomeoutasphysicalsymptoms,withfatigueasoneofthemostcommonmanifestations."Manypeoplewhoareextremelyfatigueddon'tevenknowthey'redepressed,"Dr.Bulettesays."They'resobusydistractingthemselvesorjustworryingaboutbeingtiredthattheydon'trecognizetheirdepression.”

Thereisagreatdealyoucandoonyourowntodealwithbothsevereprolongedfatigueandthoseperiodicwashed-outfeelings.Vitaminsandtranquilizersarealmostnevertherightanswer,sleepingpillsandalcoholarecounterproductive,andcaffeineisatbestatemporarysolutionthatcanbackfirewithabuseandcauselife-disruptingsymptomsofanxiety.Instead,youmighttry:

Diet

Ifyoueatasmallbreakfastornoneatall,you'relikelytoexperiencemid-morningfatigue,theresultofadropinbloodsugar,whichyourbodyandbraindependonforenergy.Forpeakenergyinthemorning,besuretoeataproperbreakfast,lowinsugarandfairlyhighinprotein,whichwillprovideasteadysupplyofbloodsugarthroughoutthemorning.Coffeeandadoughnutarealmostworsethannothi