2025年全國海船船員考試《輪機部(輪機英語8001)》測試題及答案一、單項選擇題（每題1分，共50分）1.Whichofthefollowingisthemainfunctionofacentrifugalpump?A.Togeneratehighpressure.B.Totransferlargevolumesoffluidatrelativelylowpressure.C.Tohandleviscousfluidsefficiently.D.Tooperateathighspeedswithlowefficiency.Answer:B.Centrifugalpumpsaredesignedtotransferlargevolumesoffluidatrelativelylowpressure.Theyworkbasedontheprincipleofcentrifugalforce.Highpressuregenerationismorecharacteristicofpositivedisplacementpumps.Centrifugalpumpsarenotveryefficientforhandlingviscousfluids,andtheygenerallyoperateathighefficiencywhenrunningatappropriatespeeds.2.Thegovernorofadieselengineisusedto______.A.controltheenginespeedB.regulatethefuelinjectiontimingC.adjustthevalvetimingD.lubricatetheenginepartsAnswer:A.Themainfunctionofagovernorinadieselengineistocontroltheenginespeed.Itsensesthechangeinenginespeedandadjuststhefuelsupplyaccordinglytomaintainarelativelyconstantspeedunderdifferentloadconditions.Fuelinjectiontimingisadjustedbythefuelinjectionsystem,valvetimingisrelatedtothecamshaftandvalvemechanism,andlubricationisthefunctionofthelubricatingsystem.3.Inamarinesteamboiler,thefunctionofthewaterlevelregulatoristo______.A.controlthesteampressureB.maintainaconstantwaterlevelC.adjustthefuelsupplyD.cleantheboilertubesAnswer:B.Thewaterlevelregulatorinamarinesteamboilerisresponsibleformaintainingaconstantwaterlevelintheboiler.Steampressureiscontrolledbythepressurecontrolsystem.Fuelsupplyisadjustedaccordingtothesteamdemandandisrelatedtothecombustioncontrolsystem.Cleaningofboilertubesisdonebysootblowersorothercleaningdevices.4.Thefunctionofaheatexchangeristo______.A.increasethetemperatureofafluidB.decreasethetemperatureofafluidC.transferheatbetweentwofluidsD.storeheatAnswer:C.Aheatexchangerisadevicethattransfersheatbetweentwofluidswithoutallowingthemtomix(inmostcases).Itcaneitherincreaseordecreasethetemperatureofafluiddependingonthetemperaturedifferencebetweenthetwofluidsinvolvedintheheattransferprocess.Itsprimarypurposeisheattransfer,notheatstorage.5.Themostcommontypeofmarinedieselenginelubricatingoilis______.A.mineraloilB.syntheticoilC.vegetableoilD.animaloilAnswer:A.Mineraloilisthemostcommontypeoflubricatingoilusedinmarinedieselengines.Syntheticoilsaremoreexpensiveandareusedinsomespecialapplicationswherehighperformancelubricationisrequired.Vegetableandanimaloilsarenotcommonlyusedinmarinedieselenginesduetotheirpooroxidationstabilityandotherlimitations.6.Thestartingairsystemofamarinedieselengineprovidescompressedairto______.A.starttheengineB.cooltheengineC.lubricatetheengineD.cleantheengineAnswer:A.Thestartingairsystemofamarinedieselenginesuppliescompressedairtotheenginecylinderstostarttheengine.Compressedairisadmittedintothecylindersattheappropriatetimetoturntheenginecrankshaftandinitiatethecombustionprocess.Coolingisdonebythecoolingsystem,lubricationbythelubricatingsystem,andcleaningbyvariouscleaningdevices.7.Inarefrigerationsystem,therefrigerantchangesfromaliquidtoavaporinthe______.A.compressorB.condenserC.evaporatorD.expansionvalveAnswer:C.Inarefrigerationsystem,therefrigerantabsorbsheatfromthesurroundingspaceandchangesfromaliquidtoavaporintheevaporator.Thecompressorcompressesthevaporrefrigerant,thecondenserrejectsheatandchangesthevaporrefrigerantbacktoaliquid,andtheexpansionvalvereducesthepressureoftheliquidrefrigerant.8.Thefunctionofafuelfilterinamarinedieselengineisto______.A.removewaterfromthefuelB.removesolidparticlesfromthefuelC.increasethefuelpressureD.regulatethefuelflowAnswer:B.Themainfunctionofafuelfilterinamarinedieselengineistoremovesolidparticlesfromthefuel.Whilesomefuelfiltersmayalsohaveawaterseparatingfunction,theirprimarypurposeistopreventsolidcontaminantsfromenteringthefuelinjectionsystem.Increasingfuelpressureisthejobofthefuelpump,andregulatingfuelflowisrelatedtothefuelcontrolsystem.9.Theterm“pistonstroke”refersto______.A.thedistancethepistontravelsfromtopdeadcentertobottomdeadcenterB.thediameterofthepistonC.thespeedofthepistonD.thevolumeofthecombustionchamberAnswer:A.Thepistonstrokeisdefinedasthedistancethepistontravelsfromtopdeadcenter(TDC)tobottomdeadcenter(BDC)orviceversa.Thediameterofthepistoniscalledthepistondiameter.Thespeedofthepistonisrelatedtotheenginespeed,andthevolumeofthecombustionchamberisadifferentparameterrelatedtotheengine'scompressionratio.10.Adieselengine'scompressionratioistheratioofthe______.A.cylindervolumeatbottomdeadcentertothecylindervolumeattopdeadcenterB.pistonareatothecylinderareaC.enginepoweratfullloadtotheenginepowerathalfloadD.fuelconsumptionathighspeedtothefuelconsumptionatlowspeedAnswer:A.Thecompressionratioofadieselengineistheratioofthecylindervolumewhenthepistonisatbottomdeadcenter(VBDC)tothecylindervolumewhenthepistonisattopdeadcenter(VTDC).Itisanimportantparameterthataffectstheengine'sperformance,efficiency,andcombustionprocess.11.Thefunctionoftheaircoolerinaturbochargeddieselengineisto______.A.increasethedensityoftheintakeairB.decreasethetemperatureoftheexhaustgasC.lubricatetheturbochargerD.cleantheintakeairAnswer:A.Inaturbochargeddieselengine,theaircooler(alsoknownasanintercooler)coolsthecompressedaircomingfromtheturbocharger.Coolingtheairincreasesitsdensity,whichallowsmoreairtoenterthecylinders,resultinginmoreefficientcombustionandincreasedenginepower.Ithasnothingtodowithexhaustgastemperaturereduction,turbochargerlubrication,oraircleaning.12.Themaindifferencebetweenafourstrokeandatwostrokedieselengineis______.A.thenumberofrevolutionsofthecrankshaftperpowerstrokeB.thetypeoffuelusedC.thesizeoftheengineD.thelubricationsystemAnswer:A.Inafourstrokedieselengine,thereisonepowerstrokeforeverytworevolutionsofthecrankshaft.Inatwostrokedieselengine,thereisonepowerstrokeforeveryrevolutionofthecrankshaft.Thetypeoffuelusedcanbethesameforbothtypesofengines,andenginesizeandlubricationsystemarenotthemaindifferentiatingfactors.13.Thefunctionofthefuelinjectionpumpinadieselengineisto______.A.meteranddeliverfueltotheinjectorsatthecorrectpressureandtimingB.mixfuelwithairC.storefuelD.filterfuelAnswer:A.Thefuelinjectionpumpinadieselengineisresponsibleformeteringthecorrectamountoffuelanddeliveringittotheinjectorsattheappropriatepressureandtiming.Mixingfuelwithairoccursinthecombustionchamber.Fuelstorageisdoneinthefueltank,andfuelfilteringisthejobofthefuelfilter.14.Inamarineelectricalsystem,thealternatorisusedto______.A.convertmechanicalenergyintoelectricalenergyB.convertelectricalenergyintomechanicalenergyC.storeelectricalenergyD.regulatetheelectricalvoltageAnswer:A.Analternatorinamarineelectricalsystemisageneratorthatconvertsmechanicalenergy(usuallyfromtheengine)intoelectricalenergy.Convertingelectricalenergyintomechanicalenergyisthefunctionofanelectricmotor.Electricalenergystorageisdonebybatteries,andvoltageregulationisthefunctionofvoltageregulators.15.Thefunctionofthemainswitchboardinamarineelectricalsystemisto______.A.distributeelectricalpowertovariousloadsB.generateelectricalpowerC.storeelectricalpowerD.controlthespeedofelectricmotorsAnswer:A.Themainswitchboardinamarineelectricalsystemisusedtodistributeelectricalpowergeneratedbythealternatorstovariouselectricalloadsontheship.Powergenerationisdonebythealternators,powerstoragebybatteries,andmotorspeedcontrolisachievedbymotorcontroldevices.16.Thepurposeoftheballastwatersystemonashipisto______.A.adjusttheship'sdraft,trim,andstabilityB.cooltheengineC.providedrinkingwaterD.cleantheship'shullAnswer:A.Theballastwatersystemonashipisusedtoadjusttheship'sdraft,trim,andstability.Bytakinginordischargingballastwater,theship'sweightdistributioncanbechangedtooptimizeitsperformanceindifferentoperatingconditions.Enginecoolingisdonebytheenginecoolingsystem,drinkingwaterisprovidedbythefreshwatersupplysystem,andhullcleaningisadifferentoperation.17.Thefunctionofthepurifierinamarineoilpurificationsystemisto______.A.separatewaterandimpuritiesfromtheoilB.increasetheviscosityoftheoilC.changethecoloroftheoilD.addadditivestotheoilAnswer:A.Apurifierinamarineoilpurificationsystemisusedtoseparatewaterandsolidimpuritiesfromtheoil.Itworksbasedontheprincipleofcentrifugalforce.Itdoesnotincreasetheviscosityoftheoil,changeitscolor,oraddadditives.18.Theterm“specificgravity”ofaliquidrefersto______.A.theratioofthedensityoftheliquidtothedensityofwaterB.theweightoftheliquidperunitvolumeC.thevolumeoftheliquidperunitweightD.thetemperatureatwhichtheliquidboilsAnswer:A.Specificgravityistheratioofthedensityofaliquidtothedensityofwaterataspecifiedtemperature(usually4°C).Weightperunitvolumeisdensity,volumeperunitweightisthereciprocalofdensity,andtheboilingtemperatureisadifferentphysicalproperty.19.Thefunctionofthereliefvalveinahydraulicsystemisto______.A.limitthemaximumpressureinthesystemB.increasetheflowrateofthehydraulicfluidC.lubricatethehydrauliccomponentsD.filterthehydraulicfluidAnswer:A.Areliefvalveinahydraulicsystemisdesignedtoopenwhenthepressureinthesystemexceedsapresetvalue,therebylimitingthemaximumpressureinthesystem.Ithasnoeffectontheflowrate,lubrication,orfilteringofthehydraulicfluid.20.Themainadvantageofavariablepitchpropelleris______.A.itcanadjustthepropellerpitchtosuitdifferentoperatingconditionsB.itischeaperthanafixedpitchpropellerC.ithasahigherefficiencyatallspeedsD.itrequireslessmaintenanceAnswer:A.Avariablepitchpropellercanchangeitspitchangle,whichallowsittoadjusttodifferentoperatingconditionssuchasdifferentshipspeeds,loads,andseaconditions.Itisgenerallymoreexpensivethanafixedpitchpropeller,doesnothavehigherefficiencyatallspeeds,andmayrequiremoremaintenanceduetoitscomplexmechanism.21.Thefunctionoftheexhaustgasboilerinamarinepowerplantisto______.A.recoverheatfromtheexhaustgastogeneratesteamB.reducethenoiseoftheexhaustgasC.cleantheexhaustgasD.increasethetemperatureoftheexhaustgasAnswer:A.Anexhaustgasboilerinamarinepowerplantusestheheatfromtheengine'sexhaustgastogeneratesteam.Thisisaformofwasteheatrecovery,whichimprovestheoverallefficiencyofthepowerplant.Ithasnothingtodowithnoisereduction,exhaustgascleaning,orincreasingexhaustgastemperature.22.Theterm“flashpoint”ofafuelrefersto______.A.thelowesttemperatureatwhichthefuelgivesoffenoughvaportoformanignitablemixturewithairB.thetemperatureatwhichthefuelstartstoburncontinuouslyC.thetemperatureatwhichthefuelchangesfromaliquidtoavaporD.themaximumtemperaturethefuelcanwithstandwithoutdecompositionAnswer:A.Theflashpointofafuelisthelowesttemperatureatwhichthefuelgivesoffenoughvaportoformanignitablemixturewithairwhenanignitionsourceisapplied.Thetemperatureatwhichthefuelstartstoburncontinuouslyisthefirepoint.Changingfromaliquidtoavaporisrelatedtotheboilingpoint,andthemaximumtemperaturewithoutdecompositionisadifferentproperty.23.Thefunctionofthesteeringgearsystemonashipisto______.A.controlthedirectionoftheshipB.controlthespeedoftheshipC.maintainthestabilityoftheshipD.generateelectricalpowerAnswer:A.Thesteeringgearsystemonashipisusedtocontrolthedirectionoftheshipbyturningtherudder.Controllingtheship'sspeedisthefunctionofthepropulsionsystem,maintainingstabilityisrelatedtotheship'sdesign,ballastsystem,etc.,andpowergenerationisdonebythepowerplant.24.Themaincomponentofahydraulicsteeringgearsystemis______.A.thehydraulicpump,hydrauliccylinder,andcontrolvalvesB.theelectricmotor,gearbox,andchaindriveC.thesteamturbine,condenser,andpumpD.theaircompressor,airtank,andcontrolvalvesAnswer:A.Ahydraulicsteeringgearsystemtypicallyconsistsofahydraulicpumptoprovidethehydraulicpressure,hydrauliccylinderstomovetherudder,andcontrolvalvestoregulatetheflowanddirectionofthehydraulicfluid.Electricmotorbased,steamturbinebased,andaircompressorbasedsystemsarenotthemaincomponentsofahydraulicsteeringgearsystem.25.Thefunctionoftheboilersafetyvalveisto______.A.preventtheboilerpressurefromexceedingthesafelimitB.controlthewaterlevelintheboilerC.regulatethefuelsupplytotheboilerD.cleantheboilertubesAnswer:A.Theboilersafetyvalveisacrucialsafetydevicethatopenswhentheboilerpressureexceedsthepresetsafelimit,allowingsteamtoescapeandpreventingtheboilerfromoverpressurizing.Waterlevelcontrolisdonebythewaterlevelregulator,fuelsupplyregulationisbythecombustioncontrolsystem,andtubecleaningisbysootblowers.26.Inamarinedieselengine,thecrankshaftissupportedby______.A.mainbearingsB.connectingrodbearingsC.thrustbearingsD.alloftheaboveAnswer:A.Thecrankshaftinamarinedieselengineissupportedbymainbearings.Connectingrodbearingsconnecttheconnectingrodstothecrankshaftpins,andthrustbearingsareusedtoabsorbtheaxialthrust.Whileallthesebearingsareimportantintheengine,themainsupportforthecrankshaftisprovidedbythemainbearings.27.Thefunctionoftheoilmistdetectorinadieselengineisto______.A.detectthepresenceofoilmistinthecrankcaseB.measuretheviscosityofthelubricatingoilC.adjusttheoilpressureinthelubricatingsystemD.cleanthelubricatingoilAnswer:A.Anoilmistdetectorinadieselengineisdesignedtodetectthepresenceofoilmistinthecrankcase.Thepresenceofoilmistcanbeanindicationofapotentialproblemsuchasoverheatingorabnormalwear.Measuringoilviscosityisdonebyviscometers,adjustingoilpressureisbythepressureregulatingvalve,andcleaningtheoilisbytheoilpurificationsystem.28.Themostimportantfactoraffectingtheperformanceofacentrifugalpumpis______.A.thespeedoftheimpellerB.thesizeofthepumpcasingC.thecolorofthepumpD.thematerialoftheimpellerAnswer:A.Thespeedoftheimpelleristhemostimportantfactoraffectingtheperformanceofacentrifugalpump.Theimpellerspeeddeterminesthecentrifugalforcegenerated,whichinturnaffectstheflowrateandheadofthepump.Thepumpcasingsize,color,andimpellermaterialhavesecondaryeffectsonthepump'sperformance.29.Thefunctionofthecondenserinasteampowerplantisto______.A.convertsteamintowaterB.increasethetemperatureofthesteamC.storesteamD.cleanthesteamAnswer:A.Inasteampowerplant,thecondensercoolstheexhauststeamfromthesteamturbine,convertingitbackintowater(condensate).Thiswatercanthenbepumpedbacktotheboilerforreuse.Itdoesnotincreasethesteamtemperature,storesteam,orcleanthesteam.30.Theterm“cavitation”inapumprefersto______.A.theformationandcollapseofvaporbubblesintheliquidduetolowpressureB.thewearandtearofthepumpimpellerC.theleakageoffluidfromthepumpD.theincreaseinthetemperatureofthepumpAnswer:A.Cavitationinapumpoccurswhenthepressureintheliquiddropsbelowthevaporpressure,causingvaporbubblestoform.Thesebubblesthencollapsewhentheymovetoaregionofhigherpressure,whichcancausedamagetothepumpcomponents.Wearandtear,leakage,andtemperatureincreasearedifferentphenomena.31.Thefunctionofthefuelinjectorinadieselengineisto______.A.atomizethefuelandinjectitintothecombustionchamberB.mixthefuelwithairoutsidethecombustionchamberC.storethefuelD.filterthefuelAnswer:A.Thefuelinjectorinadieselengineatomizesthefuelintofinedropletsandinjectsitintothecombustionchamberatthecorrecttimeandpressure.Mixingfuelwithairoccursmainlyinthecombustionchamber.Fuelstorageisinthefueltank,andfuelfilteringisbythefuelfilter.32.Themainfunctionofthelubricatingoilinadieselengineisto______.A.reducefrictionandwearbetweenmovingpartsB.increasethetemperatureoftheengineC.cleantheexhaustgasD.generateelectricalpowerAnswer:A.Theprimaryfunctionoflubricatingoilinadieselengineistoreducefrictionandwearbetweenmovingparts.Italsohelpsincooling,sealing,andcleaningtheenginecomponents.Itdoesnotincreasetheenginetemperature,cleantheexhaustgas,orgenerateelectricalpower.33.Thefunctionofthewatercooledjacketaroundthecylindersofadieselengineisto______.A.removeheatfromthecylindersB.increasethecompressionratiooftheengineC.lubricatethepistonsD.cleanthecylindersAnswer:A.Thewatercooledjacketaroundthecylindersofadieselenginecirculatescoolingwatertoremoveheatgeneratedduringthecombustionprocess.Thishelpstopreventoverheatingofthecylindersandmaintaintheengine'sperformanceandreliability.Ithasnodirectrelationtoincreasingthecompressionratio,pistonlubrication,orcylindercleaning.34.Thetypeofbearingcommonlyusedinthemainshaftofamarinedieselengineis______.A.journalbearingB.ballbearingC.rollerbearingD.thrustbearingAnswer:A.Journalbearingsarecommonlyusedinthemainshaftofamarinedieselengine.Theyprovideasmoothandcontinuoussupportfortherotatingshaft.Ballandrollerbearingsaremorecommonlyusedinapplicationswherehighspeedandlowfrictionoperationisrequired.Thrustbearingsareusedtohandleaxialthrust.35.Thefunctionofthetachometerinadieselengineisto______.A.measurethespeedoftheengineB.measurethetemperatureoftheengineC.measurethepressureofthelubricatingoilD.measuretheleveloffuelinthetankAnswer:A.Atachometerinadieselengineisusedtomeasurethespeedoftheengine,usuallyinrevolutionsperminute(RPM).Measuringtemperatureisdonebythermometers,pressurebypressuregauges,andfuellevelbyfuellevelsensors.36.Thepurposeofthescavengingprocessinadieselengineisto______.A.removetheexhaustgasfromthecylindersandfillthemwithfreshairB.increasethecompressionratiooftheengineC.lubricatetheenginecomponentsD.cleanthefuelinjectionsystemAnswer:A.Thescavengingprocessinadieselengineistoremovetheexhaustgasfromthecylindersafterthecombustionprocessandfillthemwithfreshairforthenextcycle.Ithasnodirectrelationtoincreasingthecompressionratio,lubricatingcomponents,orcleaningthefuelinjectionsystem.37.Thefunctionoftheeconomizerinamarinesteamboileristo______.A.preheatthefeedwaterusingtheheatfromtheexhaustgasB.increasethesteampressureintheboilerC.regulatethewaterlevelintheboilerD.cleantheboilertubesAnswer:A.Aneconomizerinamarinesteamboilerpreheatsthefeedwaterusingtheheatfromtheexhaustgas.Thisimprovestheoverallefficiencyoftheboilerbyreducingtheamountoffuelneededtoheatthewatertotheboilingpoint.Itdoesnotincreasesteampressure,regulatewaterlevel,orcleantubes.38.Themaindifferencebetweenadirectactingandapilotoperatedreliefvalveis______.A.thewaytheyareactuatedB.thetypeoffluidtheycanhandleC.thepressurerangetheycanoperateinD.thesizeofthevalveAnswer:A.Adirectactingreliefvalveisactuateddirectlybythesystempressureactingonaspringloadedvalvedisc.Apilotoperatedreliefvalveusesapilotvalvetocontroltheopeningandclosingofthemainvalve.Thetypeoffluid,pressurerange,andsizearenotthemaindifferentiatingfactors.39.Thefunctionofthecompressorinarefrigerationsystemisto______.A.compresstherefrigerantvaporandincreaseitspressureandtemperatureB.expandtherefrigerantliquidanddecreaseitspressureandtemperatureC.transferheatfromtherefrigeranttothesurroundingenvironmentD.storetherefrigerantAnswer:A.Inarefrigerationsystem,thecompressorcompressesthelowpressure,lowtemperaturerefrigerantvaporcomingfromtheevaporator,increasingitspressureandtemperature.Expansionoftherefrigerantisdonebytheexpansionvalve,heattransfertotheenvironmentisinthecondenser,andrefrigerantstorageisinthereceiver.40.Theterm“horsepower”isaunitof______.A.powerB.energyC.forceD.pressureAnswer:A.Horsepowerisaunitofpower,whichmeasurestherateatwhichworkisdone.Energyismeasuredinjoulesorotherenergyunits,forceismeasuredinnewtons,andpressureismeasuredinpascalsorotherpressureunits.41.Thefunctionoftheaircompressoronashipisto______.A.compressairforvarioususessuchasstartingengines,operatingpneumatictoolsB.cooltheengineC.generateelectricalpowerD.cleantheexhaustgasAnswer:A.Anaircompressoronashipcompressesairforvariousapplications,includingstartingdieselengines,operatingpneumatictools,andpoweringsomecontrolsystems.Ithasnothingtodowithenginecooling,powergeneration,orexhaustgascleaning.42.Thefunctionofthedesalinationplantonashipisto______.A.convertseawaterintofreshwaterB.increasethesalinityofseawaterC.storeseawaterD.cleantheseawaterAnswer:A.Adesalinationplantonashipisusedtoconvertseawaterintofreshwaterbyremovingthesaltandotherimpurities.Itdoesnotincreasesalinity,storeseawater,orjustcleanseawaterwithoutthedesalinationprocess.43.Themaincomponentofafirefightingsystemonashipis______.A.thefirepump,firehydrants,andhosesB.theelectricgenerator,switchboard,andcablesC.theaircompressor,airtank,andcontrolvalvesD.thesteamturbine,condenser,andpumpAnswer:A.Afirefightingsystemonashiptypicallyconsistsofafirepumptosupplywaterunderpressure,firehydrantsforaccesstothewater,andhosestodirectthewaterontothefire.Electricgeneration,aircompression,andsteamturbinebasedsystemsarenotthemaincomponentsofafirefightingsystem.44.Thefunctionofthebilgepumponashipisto______.A.removewaterfromthebilgeB.increasethespeedoftheshipC.maintainthestabilityoftheshipD.generateelectricalpowerAnswer:A.Thebilgepumponashipisusedtoremovewaterthathascollectedinthebilge(thelowestpartoftheship'shull).Ithasnorelationtoincreasingshipspeed,maintainingstability,orpowergeneration.45.Thefunctionoftheantiicingsystemonashipisto______.A.preventiceformationontheship'ssuperstructure,decks,andequipmentB.increasethetemperatureoftheengineC.cleantheexhaustgasD.generateelectricalpowerAnswer:A.Theantiicingsystemonashipisdesignedtopreventiceformationontheship'ssuperstructure,decks,andequipment,whichcanbedangerousandaffecttheship'soperation.Itdoesnotincreaseenginetemperature,cleanexhaustgas,orgeneratepower.46.Thefunctionoftheautomaticcontrolsysteminamarinepowerplantisto______.A.monitorandcontroltheoperationofvariousequipmentandsystemstoensuresafeandefficientoperationB.increasethefuelconsumptionofthepowerplantC.reducethereliabilityofthepowerplantD.generatemorenoiseAnswer:A.Theautomaticcontrolsysteminamarinepowerplantmonitorsandcontrolstheoperationofvariousequipmentandsystemssuchasengines,boilers,generators,etc.Itensuressafe,efficient,andstableoperation.Itdoesnotincreasefuelconsumption,reducereliability,orgeneratemorenoise.47.Thefunctionofthemufflerinamarineengineexhaustsystemisto______.A.reducethenoiseoftheexhaustgasB.increasethetemperatureoftheexhaustgasC.cleantheexhaustgasD.increasethebackpressureoftheexhaustsystemAnswer:A.Amufflerinamarineengineexhaustsystemisusedtoreducethenoiseoftheexhaustgasbyabsorbinganddissipatingthesoundenergy.Itdoesnotincreaseexhaustgastemperature,cleanthegas,orincreasebackpressure(infact,itisdesignedtominimizebackpressure).48.Thefunctionoftheshaftsealinamarinepumpisto______.A.preventtheleakageoffluidfromthepumpalongtheshaftB.increasethepressureofthefluidinthepumpC.lubricatetheshaftD.cleanthefluidAnswer:A.Theshaftsealinamarinepumppreventstheleakageoffluidfromthepumpalongtheshaft.Ithasnodirectrelationtoincreasingfluidpressure,shaftlubrication,orfluidcleaning.49.Thefunctionofthestrainerinafluidsystemisto______.A.removelargesolidparticlesfromthefluidB.increasetheviscosityofthefluidC.changethecolorofthefluidD.addadditivestothefluidAnswer:A.Astrainerinafluidsystemisusedtoremovelargesolidparticlesfromthefluid.Itdoesnotaffecttheviscosity,color,oraddadditivestothefluid.50.Thefunctionofthewaterseparatorinafuelsystemisto______.A.separatewaterfromthefuelB.increasethedensityofthefuelC.changetheflashpointofthefuelD.filterthefuelAnswer:A.Thewaterseparatorinafuelsystemisdesignedtoseparatewaterfromthefuel.Ithasnoeffectonfueldensity,flashpoint,orfinefilteringofthefuel.二、閱讀理解題（每題2分，共20分）Passage1Thedieselengineisaveryimporta