MOOC Explore the Materials-From an Atom to a Device（走进材料-从原子到器件）-北京航空航天大学 中国大学慕课答案

MOOCExploretheMaterials——FromanAtomtoaDevice（走进材料——从原子到器件）-北京航空航天大学中国大学慕课答案第一章测验1、问题：Thebasicunitofmaterialsis_____,whichcanbonddirectlytogethertoformmaterials,orconvertintoions,orassembleintomolecules.选项：A、nucleusB、electronC、protonD、atom正确答案:【atom】2、问题：Crystallinestructureisadescriptionoftheorderedarrangementofatoms,ionsormoleculesinacrystallinematerial.Weoftenuse____toillustratethe3Dstructure,whichisanarrayof'smallboxes'infinitelyrepeatinginthreespatialdirections.选项：A、unitcellB、crystallatticeC、grainD、cuboid正确答案:【crystallattice】3、问题：Atomscouldbebondedindifferentpatterns,wecallthemchemicalbonds.Thethreemaintypesofchemicalbondsaremetallic,ionicand______bonds.选项：A、atomicB、covalentC、covalenceD、molecular正确答案:【covalent】4、问题：Accordingtothedominantmaterialusedbyhumanbeing,theearlydevelopmentofmankindcanbenamedastheStoneAge,theCopperage,theBronzeAgeandthe_____age.选项：A、PolymerB、IronC、SteelD、Silicon正确答案:【Iron】5、问题：Accordingtochemicalcomposition,materialsareusuallyclassifiedasmetals,__________,polymersand_________.选项：A、alloysB、ceramicsC、inorganicD、composites正确答案:【ceramics#composites】6、问题：Atomsaremadefromevensmallerparticles.TheyareProtons,NeutronsandElectrons.选项：A、正确B、错误正确答案:【正确】7、填空题：Thesequenceofdifferentscalesismacro,mini,meso,______,nanoandatomic.正确答案:【micro】第二章测验1、问题：Metallicmaterialsaremostly______innature.选项：A、puremetalB、amorphousC、crystallineD、non-crystalline正确答案:【crystalline】2、问题：Basedonthe3-dimensionalconfigurationsofatomsincrystals,allthecrystallatticestructurescanbeclassifiedas_______crystalsystemsand______Bravaislatticesystem.选项：A、four,seventeenB、seven,fourteenC、four,sevenD、fourteen,seven正确答案:【seven,fourteen】3、问题：Asindicatedinfollowingfigure,thecrystalplaneinthecubiccellcouldbewrittenas_____.选项：A、(011)B、(110)C、(101)D、(111)正确答案:【(110)】4、问题：Steelisactuallyanalloyof_____and_____.选项：A、iron,tinB、copper,tinC、iron,carbonD、iron,copper正确答案:【iron,carbon】5、问题：Whichoneisnotthetypicalpropertyofmetallicmaterials?选项：A、goodelectricalandthermalconductorsB、solidatroomtemperatureC、brittleD、ductile正确答案:【brittle】6、问题：Becauseofthestrongbonding,metallicmaterialsusuallyhavehighpackingdensity.Typicallatticestructuresofmetalsinclude_____,_____and_____structure.选项：A、body-centeredcubicB、face-centeredcubicC、hexagonalclose-pacedstructureD、primitivecubic正确答案:【body-centeredcubic#face-centeredcubic#hexagonalclose-pacedstructure】7、问题：Analloyphasediagramisagraphicalrepresentationtoshowtherelationshipsbetweenthevariousphasesthatappearwithinthesystemunderequilibriumconditions.Inaphasediagram,usuallycompositionisplottedonthex-axisandpressureisplottedonthey-axis.选项：A、正确B、错误正确答案:【错误】第三章测验1、问题：Themajorityofmetalhasatendencytochangeinto______gradually,exceptseveralnoblemetals,duetotheexposuretotheenvironment.选项：A、alloyB、metalliccompoundsC、greycolorD、metaloxides正确答案:【metalliccompounds】2、问题：Amongvarioustypesofcorrosions,_______corrosionisthemostcommonone.选项：A、electrochemicalB、chemicalC、physicalD、biological正确答案:【electrochemical】3、问题：Alfoilscouldkeepshining,insteadofcorrosion.It’sbecauseof____,whichformsaverythinlayerofoxidizedfilmtoinhibitAlforfurthercorrosion.选项：A、thermalstabilityB、passivationC、activationD、corrosion正确答案:【passivation】4、问题：Basedontheinsertedtableofstandardelectrodepotentialsofmetals,itcouldbeinferredthat______showshighertendencytobecorrodedinaqueoussolutionat25°C.选项：A、ZincB、IronC、NickelD、Tin正确答案:【Zinc】5、问题：Inordertoreducethelossfromcorrosion,wecouldusethefollowingmethods:______.选项：A、electrochemicalprotectionB、applicationofcoatingsC、appropriatematerialsselectionD、suitabledesign正确答案:【electrochemicalprotection#applicationofcoatings#appropriatematerialsselection#suitabledesign】6、问题：Thestandardelectrodepotentialofdifferentmetalsinanaqueoussolutioncouldapproximatelyshowtheirthermodynamicstability.选项：A、正确B、错误正确答案:【正确】7、问题：Thecathodicreactionisprobablyoxygenreductionreaction(ORR)whensteeliscorrodedinanacidaqueoussolution选项：A、正确B、错误正确答案:【错误】第四章测试1、问题：______isnotthepropertyofinorganicnon-metallicmaterials.选项：A、morecomplicatecrystallinestructurethanmetalsB、nofreeelectronsC、lowmeltingtemperatureD、strongchemicalresistance正确答案:【lowmeltingtemperature】2、问题：Whichisnotcorrect?选项：A、Theordinaryceramicisnottransparentbecausetheyaremadeofultrapurerawmaterials.B、Theordinaryceramicisnottransparentbecausetheycontainimpurities.C、Theordinaryceramicisnottransparentbecausetheycontaingascavity.D、Theordinaryceramicisnottransparentbecausetheyabsorblightsandcauselightscattering.正确答案:【Theordinaryceramicisnottransparentbecausetheyaremadeofultrapurerawmaterials.】3、问题：______arethechemicalbondsininorganicnon-metallicmaterials.选项：A、ionicbondsB、mixedbondsC、metalbondsD、purecovalentbonds正确答案:【ionicbonds#mixedbonds】4、问题：Choosethegeneralpropertiesofceramicsfromthefollowing选项：A、HardB、Wear-resistantC、MagneticD、Oxidationresistant正确答案:【Hard#Wear-resistant#Oxidationresistant】5、问题：Whicharecorrectinthefollowingoptions?选项：A、Theordinaryceramicisnottransparentbecausetheycontaingascavity.B、Theordinaryceramicisnottransparentbecausetheyabsorblightsandcauselightscattering.C、Theordinaryceramicisnottransparentbecausetheycontainimpurities.D、Theordinaryceramicisnottransparentbecausetheyaremadeofultrapurerawmaterials.正确答案:【Theordinaryceramicisnottransparentbecausetheycontaingascavity.#Theordinaryceramicisnottransparentbecausetheyabsorblightsandcauselightscattering.#Theordinaryceramicisnottransparentbecausetheycontainimpurities.】6、问题：Theglasshavevariouscolorsbecausetheycontaindifferentmetalsorrareearthmetals.选项：A、正确B、错误正确答案:【正确】7、问题：Inorganicnon-metallicmaterialshavehigherthermalconductivitythanmetals.选项：A、正确B、错误正确答案:【错误】第五章测试1、问题：______isthecharacteristicunitofpolymerstructure.选项：A、AtomB、ElementC、GroupD、Monomer正确答案:【Monomer】2、问题：Choosethecharacteristicsofcopolymersfromthefollowingoptions.选项：A、Consistofsinglespeciesofrepeatingunits.B、Synthesizefromadditionpolymerization.C、Havetwoormoretypesofmonomers.D、Haveacomplexstructure正确答案:【Havetwoormoretypesofmonomers.#Haveacomplexstructure】3、问题：______arethepossiblefeaturesofpolymermaterials.选项：A、LongchainB、RepeatunitsC、MainlyinorganicD、Crystalline正确答案:【Longchain#Repeatunits#Crystalline】4、问题：______,______and______arethepolymermaterials.选项：A、StarchB、ProteinC、LeatherD、Sugar正确答案:【Starch#Protein#Leather】5、问题：ThecomponentsofaspeciesABinanadditionreactionareaddedtoadjacentatomsofasinglebond.选项：A、正确B、错误正确答案:【错误】6、问题：CrystallizationoccursabovetheGlasstransitiontemperature(Tg)andbelowthemeltingtemperature(Tm).选项：A、正确B、错误正确答案:【正确】第六章测验1、问题：Whichofthefollowingoptionsmayshowgreatercoercivity？选项：A、SoftmagneticmaterialsB、PermanentmagneticmaterialsC、BothofthemD、Uncertain正确答案:【Permanentmagneticmaterials】2、问题：Thereasonfortheresistancechangeofgiantmagnetoresistancesystemis选项：A、CurrentB、VoltageC、ChargeD、Spin正确答案:【Spin】3、问题：Whatapplicationsaresoftmagneticmaterialsmorelikelytobeusedin？选项：A、ElectromagneicsensorB、InformationstorageC、CompassD、Conductor正确答案:【Informationstorage】4、问题：Whichpropertyofelectronsisrelatedtothegiantmagnetoresistanceeffect？选项：A、SpinB、MassC、ChargeD、Speed正确答案:【Spin】5、问题：Themagnetismofferromagneticmaterialsoriginatesfrom选项：A、SpinB、MagneticmomentC、MagneticmonopoleD、Current正确答案:【Magneticmoment】6、问题：Howtoclassifythemagneticmaterialsfromtheperspectiveofsusceptibility?选项：A、ParamagneticmaterialsB、DiamagneticmaterialsC、FerromagneticmaterialsD、FerrimagneticmaterialsE、Antiferromagneticmaterials正确答案:【Paramagneticmaterials#Diamagneticmaterials#Ferromagneticmaterials#Ferrimagneticmaterials#Antiferromagneticmaterials】7、问题：Whichofthefollowingelementsisaferromagneticelement？选项：A、FeB、CuC、NiD、CoE、Zn正确答案:【Fe#Ni#Co】8、问题：Whichofthefollowingoptionsmightbeusedforinformationstorage?选项：A、SoftmagneticdevicesB、PermanentmagenticdevicesC、GiantmagnetoresistancedevicesD、Allofthem正确答案:【Permanentmagenticdevices#Giantmagnetoresistancedevices】9、问题：Thecontributionfromatomicnucleustoatomicmagneticmomentcanalwaysbeignored.选项：A、正确B、错误正确答案:【错误】第七章测验1、问题：Chiralobjectcanbesuperposedonitsmirrorimageby:选项：A、RotationsB、TranslationsC、CombinationofrotationsandtranslationsD、Noneofthem正确答案:【Noneofthem】2、问题：Whattypeofthebondsaretherebetweenthegecko'stoesetaandthewallsurface?选项：A、IonicbondB、CovalentbondC、GripD、VanderWaalsforce正确答案:【VanderWaalsforce】3、问题：Thecolorofbutterflywingsmaycomefrom选项：A、PigmentB、ReflectionC、MovingD、Moisture正确答案:【Reflection】4、问题：Propertiesofmetamaterialsmaynotbechangedby选项：A、MicrostructureB、SizeC、TemperatureD、Noneofthem正确答案:【Noneofthem】5、问题：Thechiraldrugsare选项：A、harmfulB、beneficialC、harmfulorbeneficialD、uncertaintobeharmfulorbeneficial正确答案:【uncertaintobeharmfulorbeneficial】6、问题：Whichofthefollowingfactorswillaffectthepropertiesofmetamaterials?选项：A、MaterialcompositionB、MolecularstructureC、CrystalstructureD、Macrostructurecharacteristics正确答案:【Materialcomposition#Molecularstructure#Crystalstructure#Macrostructurecharacteristics】7、问题：Whichofthefollowingpropertiesmaybeaffectedbymetamaterialstructure?选项：A、OpticalpropertiesB、MechanicalpropertyC、ElectromagneticpropertiesD、Thermalproperties正确答案:【Opticalproperties#Mechanicalproperty#Electromagneticproperties#Thermalproperties】8、问题：Whichofthefollowingoptionshaschiralcharacteristics？选项：A、HurricaneB、AminoacidC、ProteinD、DNAE、Spiralnebula正确答案:【Hurricane#Aminoacid#Protein#DNA#Spiralnebula】9、问题：Thereisonlyonechiralcenterinchiralmolecules.选项：A、正确B、错误正确答案:【错误】10、问题：Metamaterialsdonotexistinnature。选项：A、正确B、错误正确答案:【错误】第八章测验1、问题：______areadvantagesofrenewableenergy.选项：A、canbereplenishedonahumantimescaleB、NocarbondioxideemissionC、existoverwidegeographicalareasD、canuseitanytimeandanywhere正确答案:【canbereplenishedonahumantimescale#Nocarbondioxideemission#existoverwidegeographicalareas】2、问题：ThecharacteristicsofLi-ionbatteriesinclude_______.选项：A、highenergydensityB、longcyclelifeC、highvoltageD、highself-dischargerate正确答案:【highenergydensity#longcyclelife#highvoltage】3、问题：______arereasonsforchoosingLiasanimportantbatterymaterial.选项：A、itisthelowestreductionpotentialB、itisthethirdlightestelementC、ithassmallestionicradiusD、itametal.正确答案:【itisthelowestreductionpotential#itisthethirdlightestelement#ithassmallestionicradius】4、问题：Fuelcellcanconvertchemicalenergytoelectricalenergy.选项：A、正确B、错误正确答案:【正确】5、问题：Energycanbecreatedordestroyed.选项：A、正确B、错误正确答案:【错误】6、问题：Renewableenergycanmatchtheclients'sneedsanytimeandanywhere,inaddition,it'sconstructionischeap.选项：A、正确B、错误正确答案:【错误】第九章测验1、问题：ThethermoelectricconversionefficiencyisdeterminedbythefigureofmeritZT,______isnottheparameterwhicheffectthevalueofZT.选项：A、electricalconductivityB、thermalconductivityC、temperaturegradientD、current正确答案:【current】2、问题：______and______arefundamentalphysicalphenomenon,theircorrespondingenergycanbeconvertedviathermoelectricmaterials.选项：A、OpticB、acousticC、thermalD、electric正确答案:【thermal#electric】3、问题：______arestrategiesfordevelopingwide-gapthermoelectrics选项：A、reducingthermalconductivityB、improvingtheconductivityC、symmetriccrystalstructureD、Layeredstructure正确答案:【reducingthermalconductivity#improvingtheconductivity#Layeredstructure】4、问题：______aretheselectionrulesofhighlyeffectivethermoelectrics.选项：A、wide-gapB、crystalsC、layeredD、asymmetricstructures正确答案:【wide-gap#crystals#layered#asymmetricstructures】5、问题：Thermoelectricphenomenoncanbeappliedinelectroniccooling.选项：A、正确B、错误正确答案:【正确】6、问题：Seebeckeffectindicatesthatthetemperaturegradientproducesthemagneticfield.选项：A、正确B、错误正确答案:【错误】第十章测验1、问题：Graphenecanbepeeledoffbytapefrombulkgraphite,becausethe___forcebetweenthelayersisprettyweak.选项：A、electrostaticforceB、vanderWaalsC、covalentbondD、ionicbond正确答案:【vanderWaals】2、问题：_________isthemostpromisingmethodtogetlargeareaandhigh-quality2Dmaterialsfortheapplicationsofelectronics.选项：A、MechanicalexfoliationB、IntercalationandSelectiveetchingC、HydrothermalD、Chemicalvapordeposition(CVD)正确答案:【Chemicalvapordeposition(CVD)】3、问题：Comparedtobulkmaterialsandothernanomaterials,graphenehasthefollowingadvantages:______.选项：A、thethinnestmaterialsB、flexibleandtransparentC、highratioofsurfaceatomsD、quantumphenomena正确答案:【thethinnestmaterials#flexibleandtransparent#highratioofsurfaceatoms#quantumphenomena】4、问题：Generally,therearetwodifferentstrategiestogetultrathin2Dmaterials:________methodand_________method.选项：A、top-downB、topgrowthC、bottom-upD、bottomgrowth正确答案:【top-down#bottom-up】5、问题：For2Dmaterials,thefollowingmethodshavebeendevelopedaseffectiveonestotunetheirproperties:____________.选项：A、defectsB、dopingoralloyingC、phaseengineeringD、heterostructureE、intercalation正确答案:【defects#dopingoralloying#phaseengineering#heterostructure#intercalation】6、问题：2Dmaterialscanbeappliedinsemiconductors,quantumdevicesandenergydevices.选项：A、正确B、错误正确答案:【正确】第十一章测验1、问题：Inordertoachievebothflexibleandelectroactiveinmaterialsanddevices,onestrategyistointegrate____withthinsizeontoflexiblesubstrate.选项：A、electronicsB、semiconductorsC、metalsD、polymer正确答案:【electronics】2、问题：Forapolymertobeabletoconductelectriccurrent,itmustconsistalternatelyof_____and_____bondsbetweenthecarbonatoms.选项：A、single,singleB、double,doubleC、single,doubleD、double,triple正确答案:【single,double】3、问题：Torealizesensingfunctions,materialswithenergyconversionabilitiesarecrucialfundamentals.Typicalenergyconversionphenomenainmaterialsincludes___________.选项：A、piezoelectricB、pyroelectricC、thermoelectricD、triboelectricE、photovoltaic正确答案:【piezoelectric#pyroelectric#thermoelectric#triboelectric#photovoltaic】4、问题：Whichphenomenaisaboutenergyconversionbetweenmechanicalenergyandelectricalenergy?选项：A、piezoelectricB、pyroelectricC、thermoelectricD、triboelectricE、photovoltaic正确答案:【piezoelectric#triboelectric】5、问题：Pressureandstrainsensorscoulddetectpressureandstrainchangesthroughseveraltransductionprinciples,including________.选项：A、capacitanceB、piezoresistivityC、piezoelectricityD、triboelectricity正确答案:【capacitance#piezoresistivity#piezoelectricity#triboelectricity】6、问题：Thereareusuallytwowaystomakestretchableelectronics.OneiscalledGeometricEngineering,whichmeansplacingelectronicsinoronintrinsicallystretchableorganicmaterials.选项：A、正确B、错误正确答案:【错误】FinalExam1、问题：Polymersarecomposedofmonomerswhicharechemicallyheldtogetherbychemicalbonds.Thesebondsaremostly___.选项：A、hydrogenbondsB、ionicbondsC、covalentbondsD、vanderwaalsinteraction正确答案:【covalentbonds】2、问题：ThethermoelectricconversionefficiencyisdeterminedbythefigureofmeritZT,______isnottheparameterwhicheffectthevalueofZT.选项：A、electricalconductivityB、currentC、thermalconductivityD、temperaturegradient正确答案:【current】3、问题：______isnotthepolymermaterial.选项：A、ProteinB、SugarC、LeatherD、Starch正确答案:【Sugar】4、问题：Theenergyissuesdon’tinclude______选项：A、energyconversionB、energycrisisC、pollutionandemissionD、energysecurity正确答案:【energyconversion】5、问题：______arenotcharacteristicsofli-ionbatteries.选项：A、longcyclelifeB、highenergydensityC、highself-dischargerateD、highvoltage正确答案:【highself-dischargerate】6、问题：Atomscouldbebondedindifferentpatterns.Wecallthemchemicalbonds.Thethreemaintypesofchemicalbondsaremetallic,ionicand______bonds.选项：A、atomicB、covalenceC、covalentD、molecular正确答案:【covalent】7、问题：Crystallinestructureisadescriptionoftheorderedarrangementofatoms,ionsormoleculesinacrystallinematerial.Weoftenuse____toillustratethe3Dstructure,whichisanarrayof'smallboxes'infinitelyrepeatinginthreespatialdirections.选项：A、unitcellB、crystallatticeC、grainD、cuboid正确答案:【crystallattice】8、问题：Basedonthe3-dimensionalconfigurationsofatomsincrystals,allthecrystallatticestructurescanbeclassifiedas_______crystalsystemsand______Bravaislatticesystem.选项：A、four,seventeenB、seven,fourteenC、four,sevenD、fourteen,seven正确答案:【seven,fourteen】9、问题：Asindicatedinfollowingfigure,thecrystalplaneinthecubiccellcouldbewrittenas_____.选项：A、(010)B、(100)C、(001)D、(110)正确答案:【(100)】10、问题：Steelisactuallyanalloyof_____and_____.选项：A、iron,tinB、copper,tinC、iron,carbonD、iron,copper正确答案:【iron,carbon】11、问题：Analloyphasediagramisagraphicalrepresentationtoshowtherelationshipsbetweenthevariousphasesthatappearwithinthesystemunderequilibriumconditions.Inaphasediagram,usually_____isplottedasthex-axisand______isplottedasthey-axis.选项：A、composition,phaseB、temperature,compositionC、composition,pressureD、composition,temperature正确答案:【composition,temperature】12、问题：Amongvarioustypesofcorrosions,_______corrosionisthemostcommonone.选项：A、electrochemicalB、chemicalC、physicalD、biological正确答案:【electrochemical】13、问题：Alfoilscouldkeepshining,insteadofcorrosion.It’sbecauseof____,whichformsaverythinlayerofoxidizedfilmtoinhibitAlforfurthercorrosion.选项：A、thermalstabilityB、passivationC、activationD、corrosion正确答案:【passivation】14、问题：Basedontheinsertedtableofstandardelectrodepotentialsofmetals,itcouldbeinferredthat______showshigherthermodynamicactivityinaqueoussolutionat25°C.选项：A、ZincB、IronC、NickelD、TinE、notsure正确答案:【Zinc】15、问题：Amongvariousstrategiestoprepare2Dmaterials,_________isthemostpromisingonetogetlargeareaandhigh-quality2Dmaterialsfortheapplicationsofelectronics.选项：A、MechanicalexfoliationB、IntercalationandSelectiveetchingC、HydrothermalD、Chemicalvapordeposition(CVD)正确答案:【Chemicalvapordeposition(CVD)】16、问题：Theformationofcrystalshavetwosteps:nucleationandgrowth.InordertopreparelargescalegraphenesinglecrystalthroughChemicalvapordeposition(CVD),howcanwetunethenucleationandgrowthrate?选项：A、HighnucleationdensityandslowgrowthrateB、HighnucleationdensityandfastgrowthrateC、LownucleationdensityandfastgrowthrateD、Highnucleationdensityandslowgrowthrate正确答案:【Lownucleationdensityandfastgrowthrate】17、问题：Inordertoevaluatetheclosed-packeddensityofdifferentlatticestructure,wefindaparametercalledAtomicPackingFactor(APF),whichmeanstheratioof____to____.选项：A、volumeofatomsinunitcell,volumeofunitcellB、areaofatomsinunitcell,areaofunitcellC、volumeofvoidsinunitcell,volumeofunitcellD、areaofvoidsinunitcell,areaofunitcell正确答案:【volumeofatomsinunitcell,volumeofunitcell】18、问题：Thedivisionofsoftmagneticmaterialsandhardmagneticmaterialsisbasedon_______.选项：A、CoercivityB、MagnetizationC、SusceptibilityD、Magneticfield正确答案:【Coercivity】19、问题：ThecompassinventedinancientChinamaybemadeof选项：A、ParamagneticmaterialB、FerrimagneticmaterialC、AntiferromagneticmaterialD、Diamagneticmaterial正确答案:【Ferrimagneticmaterial】20、问题：______arebelongingtoenergystoragebattery.选项：A、leadacidbatteryB、Li-ionbatteryC、solarcellD、nickelmetalhydridebattery正确答案:【leadacidbattery#Li-ionbattery#nickelmetalhydridebattery】21、问题：______areadvantagesofrenewableenergy.选项：A、canbereplenishedonahumantimescaleB、existoverwidegeographicalareasC、canuseitanytimeandanywhereD、Nocarbondioxideemission正确答案:【canbereplenishedonahumantimescale#existoverwidegeographicalareas#Nocarbondioxideemission】22、问题：Accordingtochemicalcomposition,materialsareusuallyclassifiedasmetals,__________,_________andcomposites.选项：A、ceramicsB、inorganicC、polymersD、nanomaterialsE、functionalmaterials正确答案:【ceramics#polymers】23、问题：Metallicmaterialsaremostlycrystallineinnature.Becauseofthestrongbonding,metallicmaterialsusuallyhavehighpackingdensity.Typicallatticestructuresofmetalsinclude_____,_____and_____structure.选项：A、body-centeredcubicB、face-centeredcubicC、hexagonalclose-pacedstructureD、primitivecubic正确答案:【body-centeredcubic#face-centeredcubic#hexagonalclose-pacedstructure】24、问题：Generally,therearetwodifferentstrategiestogetultrathin2Dmaterials:________methodand_________method.选项：A、topgrowthB、top-downC、bottomgrowthD、bottom-up正确答案:【top-down#bottom-up】25、问题：Thereareusuallytwo