北京航空航天大学2007年博士研究生入学考试英语试题

北京航空航天大学2007年博士研究生入学考试英语试题PartⅠListeningComprehension(20points)(略)PartⅡReadingComprehension(30points)Directions:Therearefourpassagesinthepart.Eachpassageisfollowedbysomequestionsorunfinishedstatements.Foreachofthem,thereare4choicesmarkedA,B,CandD．Readthepassagescarefullyanddecideonthebestchoice.ThenmarkthecorrespondingletterontheANSWERSHEETwithasinglelinethroughthecenter.Passage1Scientistsnowtendtoagreethatthenoiselevelforpotentialhearinglossbeginsatabout70decibels.Someofthemareveryconcernedbecausenormaldailylifeoftenexposespeopletonoiselevelsofabout70decibelseveninsidetheirhomes.Citieshavealwaysbeennoisy,butnoiseisnowspreadingtoareasthatwerequietjustafewyearsago.Clearly,somethingmustbedoneornoisewillseriouslyandpermanentlymaimthepopulation.Fortunately,theknowledgeandmethodstocontrolnoisealreadyexist.Asamatteroffact,thisisoneinstancewheretheknowledgeofcontrolmethodsexceedstheknowledgeabouttheeffectsonhumanlifeandontheenvironment.Therearetwocommonmeansforcontrol.Thefirstisreducingnoiseatitssource,andthesecondischangingthesoundpathbydistanceorbyshielding.Thesecondapproachisbeingusedmoreoftentodayaspeoplebecomemoreawareofthedangerofnoise.Newbuildingcodesrequirebettersoundinsulationinhomesandapartments.Moreandmoretownsarepassingzoningordinancesthattrytosegregatenoisyfactoriesorairportsfromresidentialareas.Sound-absorbentmaterialsandconstructiondesignedtoblocksoundpathsareslowlycomingintouseinofficesandhomes.Newhighwaysarebeingbuilttoredirecttrafficnoiseupandawayfromnearbyareas.Aircraftareincreasinglybeingrequiredtousereducedpowerflightsaroundairports.Therearemanyexamplesofavailablenoisecontrolmethodsthatarenotbeingused.Moreflexiblebuildingcodeswouldpermittheuseofquieterkindsofplumbingpipes.Sound-absorbingmaterialscanreducethenoiseofmotorsandengines.Powergeneratorscanbequietedwithbaffles,exhaustsilencers,andsoundabsorbers.Trucktirescanbemadewithquietertreads.Inmanycases,thecostofbuildingquietermachinesisthesameoronlyslightlyhigherthanthatofthecurrentnoisyones.Eventhoughthenewequipmentmaycostmoreinitially,itcanprovemoreprofitableinthelongrun.Thenewjumbojets,forexample,arequieterthantheolderones,yettheyaremorepowerfulandcarrytwiceasmanypassengers.Allofthesemethodsareonlypartialmeasuresasnoisylevelscontinuetorise.Mostspecialistsinthefieldagreethatmuchofthesolutionmustcomefromeliminatingsomeofthenoiseatitssource,thereforesavingthroughpreventionthelargecostsofhearingloss.21．Thenoiselevelforpossiblehearinglossbeginsatabout______.A．30decibelsB．75decibelsC．100decibelsD．noneoftheabove22．Jetpilotsarebeingadvisedtoland______.A．onlongerrunwaysB．fromnearbyareasC．afterdarkD．withreducedpower23．Howmanypracticalmeansforcontrollingnoisedoestheauthorpresent?A．One.B．Two.C．Three.D．Four.24．Thereadercanassumethatairportofthefuturewill______.A．haverunwaysinanorth-southpatternB．belocatedinunpopulatedareasC．berequiredtowarnpassengersofhighnoiselevelsD．innearbyareas25．Jumbojetsarementionedasexamplesof______.A．efficienttransportationwithlowlevelsofnoiseB．vehiclesthatcauseseriousairpollutionC．scientificadvancesthatdomoreharmthangoodD．quieterandoldervehiclePassage2Everytimeapersoneatssomethinghemakesanutritionaldecision.Heacceptsorrejectsthefoodavailabletohimathomeformealsorsnacks.Orheselectsfoodforhimselfatmanyplacesinthecommunity,suchassupermarkets,drive-ins,restaurants,andfoodcountersindrugstores.Theseselectionsmakeadifferenceinhowanindividuallooks,howhefeels,andhowwellhecanworkandplay.Whenagoodassortmentoffoodinappropriateamountsisselectedandeaten,theconsequencesaremorelikelytobeadesirablelevelofhealthandenoughenergytoallowonetobeasactiveasoneneedsandwantstobe.Whenchoicesarelessthandesirable,theconsequencesarelikelytobepoorhealthorlimitedenergyorboth.StudiesofdietsofindividualsintheUnitedStatesshowthatfoodselectionisahighlyindividualmatter,evenamongyoungchildren.Furthermore,fartoomanyindividualsofallagesaremakingpoorchoicesdayafterdayandareeithernowlivingwiththeconsequencesorwillbeinthefuture.Nutritionistsandworkersinalliedprofessionshavebeenconcernedabouthelpingpeoplelearntoselectandenjoyawidevarietyoffoodcombinationsthatcanadduptoagooddiet.Mostpeoplebelievethattheyarewellfed—thatthechoicestheymakearegoodones.Afterall,theyarenotreallysick,neitheraretheyhungry.However,theirnutritionisusuallypoorinonerespectoranother.Milkandmilkproducts,suchascheeses,icecreamormilk,buttermilk,andyogurt,areoftenslighted.Thenpeoplemayskipmanyfruitsandvegetables,particularlythosethataregoodsourcesofvitaminsAandC．Theseincludedarkgreenleafyvegetables;deepyellowvegetables;andcitrusfruitsandvegetables,suchascabbage,tomatoes,andgreenpeppers.EveryAmericanhastherighttochoosetobeuniformedaboutnutritionaswellastobeinformed.Ifapersonbelievesthatsheiswellfed,attitudes,habits,andinformationcannotbeforceduponher.Therearelifesituations,however,thattendtocauseallindividualtowanttoknowhowtomakethebestchoices.Forexample,ayoungcoupleisstartingafamilyandmustpreparefoodforyoungchildren.26．FoodpreferenceinAmericais______.A．culturallyorientedB．inheritedC．individualisticD．accordin