2008年12月六级真题

2008年12月六级真题A卷PartIwriting(30minutes)注意：此部分试题在答题卡1上PartIIReadingComprehension(Skimmingandscanning)(15minutes)SupersizesurpriseAskanyonewhythereisanobesityepidemicandtheywilltellyouthatit’saldowntoeatingtoomuchandburningtoofewcalories.Thatexplanationappealstocommonsenseandhasdominatedeffortstogettotherootoftheobesityepidemicandreverseit/yetobesityresearchersareincreasinglydissatisfiedwithit.Manynowbelievethatsomethingelsemusthavechangedinourenvironmenttoprecipitate(促成)suchdramaticrisesinobesityoverthepast40yearsorso.Nobodyissayingthatthe“bigtwo”–reducedphysicalactivityandincreasedavailabilityoffood–arenotimportantcontributorstotheepidemic,buttheycannotexplainitall.Earlierthisyearareviewpaperby20obesityexpertssetoutthe7mostplausiblealternativeexplanationsfortheepidemic.Heretheyare.1.NotenoughsleepItiswidelybelievedthatsleepisforthebrain,notthebody.Couldashortageofshut-eyealsobehelpingtomakeusfat?Severallarge-scalestudiessuggesttheremaybealink.Peoplewhosleeplessthan7hoursanighttendtohaveahigherbodymassindexthanpeoplewhosleepmore,accordingtodatagatheredbytheUSNationalHealthandNutritionExaminationSurvey.Similarly,theUSNurses’HealthStudy,whichtracked68,000womenfor16years,foundthatthosewhosleptanaverageof5hoursanightgainedmoreweightduringthestudyperiodthanwomenwhoslept6hours,whointurngainedmorethanwhosewhoslept7.It’swellknownthatobesityimpairssleep,soperhapspeoplegetfatfirstandsleeplessafterwards.Butthenurses’studysuggeststhatitcanworkintheotherdirectiontoo:sleeplossmayprecipitateweightgain.Althoughgettingfiguresisdifficult,itappearsthatwereallyaresleepingless.In1960peopleintheUSsleptanaverageof8.5hourspernight.A2002pollbytheNationalSleepFoundationsuggeststhattheaveragehasfallentounder7hours,andthedeclineismirroredbytheincreaseinobesity.2.ClimatecontrolWehumans,likeallwarm-bloodedanimals,cankeepourcorebodytemperaturesprettymuchconstantregardlessofwhat’sgoingonintheworldaroundus.Wedothisbyalteringourmetabolic(新陈代新的)rate,shiveringorsweating.Keepingwarmandstayingcooltakeenergyunlessweareinthe“thermo-neutralzone”,whichisincreasinglywherewechoosetoliveandwork.Thereisnodenyingthatambienttemperatures(环境温度)havechangedinthepastfewdecades.Between1970and2000,theaverageBritishhomewarmedfromachilly13Cto18C.IntheUS,thechangeshavebeenattheotherendofthethermometerastheproportionofhomeswithairconditioningsrosefrom23%to47%between1978and1997.Inthesouthernstates–whereobesityratestendtobehighest–thenumberofhouseswithairconditioninghasshotupto71%from37%in1978.Couldairconditioninginsummerandheatinginwinterreallymakeadifferencetoourweight?Sadly，thereissomeevidencethatitdoes-atleastwithregardtoheating.Studiesshowthatincomfortabletemperaturesweuselessenergy.3.LesssmokingBadnews:smokersreallydotendtobethinnerthantherestofus,andquittingreallydoespackonthepounds,thoughnooneisnsurewhy.Itprobablyhassomethingtodowiththefactthatnicotineisanappetitesuppressantandappearstoupyourmetabolicrate.KatherineFlegalandcolleagresattheUSNationalCenterforHealthStatisticsinHyattsville,Maryland,havecalculatedthatpeoplekickingthehabithavebeenrespousibleforasmallbutsignificantportionoftheUSepidemicoffatness.Fromdatacollectedaroud1991bytheUSNationalHealthandNutritionExaminationSurvey,theyworkedoutthatpeoplewhohadquitinthepreviousdecadeweremuchmorelikelytobeoverweightthansmokersandpeoplewhohadneversmoked.Amongmen,forexample,nearlyhalfofquitterswereoverweightcomparedwith37%ofnon-smokersandonly28%ofsmokers.4.GeneticeffectsYourschancesofbecomingfatmaybeset,atleastinpart,beforeyouwereevenborn.childrenofboesemothersaremuchmorelikelytobecomeobestthemselveslaterinlife.Offspringofmicefedahigh-fatdietduringpregnancyaremuchmorelikelytobecomefatthantheoffspringofidenticalmicefedanormaldiet.Intriguingly,theeffectpersistsfortwoorthreegenerations.Grand-childrenofmicefedahigh-fatdietgrowupfateveniftheirownmotherisfednormally-soyoufatemayhavebeensealedevenbeforeyouwereconceived.5.Alittleolder…Somegroupsofpeoplejusthappentobefatterthanothers.surveyscarriedoutbytheUSnationalcenterforhealthstatistiesfoundthatadultsaged40to79werearoundthreetimesaslikelytobeobeseasyoungerpeople.non-whitefemalesalsotendtofallatthefatterendofthespectreum:Mexican-americanwomenare30%morelikelythanwhitewomentobeobsess,andblackwomenhavetwicetherisk.IntheUS,thesegroupsaccountforanincreasingpercentageofthepopulation.between1970and2000theUSpopulationaged35to44grewby43%.theproportionofHispanic-americansalsogrew,fromunder5%to12.5%ofthepopulation,whiletheproportionofblackAmericansincreasedfrom11%to12.3%.thesechangesmayaccountinpartfortheincreasedprevalenceofobesity.6.maturemumsMothersaroundtheworldaregettingolder.intheUK,themeanageforavingafristchildis27.3,comparedwith23.7in1970.meanageatfristbirthintheUShasalsoincreased,risingfrom21.4in1970to24.9in2000.Thiswouldbeneitherherenorthereifitwere’tfortheobservationthathavinganoldermotherseemstobeanindependentriskfactorforobesity.ResultsfromtheUSnationalheart,lungandbloodinstitute’sstudyfoundthattheoddsofachildbeingobeseincrease14%foreveryfiveextrayearsoftheirmother’sage