雨课堂学堂在线学堂云《Fundamentals of ship welding production（船舶焊接生产基础）》单元测试考核答案

注：不含主观题第1题单选题(2分)1-1The____ofmetalmaterialsrefertotheresistancetodeformationandfractureandtheabilitytodeformundervariousexternalloads(tension,compression,bending,torsion,impact,alternatingstress,etc.).AmechanicalpropertyBtensilepropertyCCompressivepropertyDFatigueresistance第2题单选题(2分)1-1Themateriallosestheabilitytoresistdeformation,whichiscalled____。AstrengthByieldphenomenonCplasticityDtoughness第3题单选题(2分)1-1____referstotheabilityofmetalmaterialstoresistplasticdeformationandfractureunderstaticload.AstrengthByieldphenomenonCplasticityDtoughness第4题多选题(2分)1-1Theplasticityofmetalsisusuallyexpressedby____and____afterfracture.AElongationafterfractureBReductionofareaCtensilestrengthDyieldstrength正确答案：AB第5题多选题(2分)1-1Whatarethethreemainmethodsofhardnesstesting?()ABrinellhardnessBRockwellhardnessCVickershardness正确答案：ABCHomework1.2第1题单选题(2分)1-2Thephenomenonthatmetalschangefromonelatticetoanotherwiththechangeoftemperatureinthesolidstateiscalled()。AisomerictransformationBColdembrittlementCElongationafterfractureDfatiguefracture第2题单选题(2分)1-2__referstotheratiooftheatomicvolumecontainedinacelltothecellvolume.Thehigherthedensity,thecloserthearrangementofatoms。ADensificationBlatticeconstantCCrystalcellDlattice第3题单选题(2分)1-2Thefinerthegrain,thehigherthestrengthandhardnessofthemetalmaterial,andthebettertheplasticityandtoughness.Thisphenomenoniscalled__。AFinegrainstrengtheningBIntergranularcorrosionCGrainrefinementDNucleationprocess第4题多选题(2分)1-2Therearemanylatticetypesofmetals.Whatarethethreemostcommontypes()ABodycenteredcubiclatticeBFacecenteredcubiclatticeCClosepackedhexagonallatticeDBodycenteredhexagonallattice正确答案：ABC第5题多选题(2分)1-2Accordingtothegeometriccharacteristicsofcrystaldefects,whichthreetypescanbeclassified()APointdefectBLinedefectCSurfacedefectDdislocation正确答案：ABCHomework1.3第1题单选题(2分)1-3ACD,wecallit____,Itmeansthattheironcarbonalloyofanycompositionisinliquidstateabovethisline.TheliquidalloyisslowlycooleduntiltheAClinebeginstoprecipitateaustenite,andslowlycooleduntiltheCDlinebeginstoprecipitatecementite.ALiquidusBSolidusCEutectoidline第2题单选题(2分)1-3AECF,called____,Itmeansthattheliquidalloyslowlycoolstothelineandallcrystallizesintosolidphase,andthenheatstothelineandstartsmelting.ALiquidusBSolidusCEutectoidline第3题单选题(2分)1-3PSKiseutectoidline,alsoknownas____Lineindicatesthatallironcarbonalloyswithwc%greaterthan0.0218%willundergoeutectoidreactionandproducepearlitewhenslowlycooledtothisline.AA1BAcmCA3第4题单选题(2分)1-3ESlineisalsocalled_____Lineisthesolidsolutionlineofcarboninaustenite.AA1BAcmCA3第5题多选题(2分)1-3Whatarethesingle-phaseregionsinthesimplifiedFe-Fe3Cphasediagram?()ALiquidphaseregion(L)BAustenitephasezone(A)CFerritephaseregionDCementite(Fe3C)正确答案：ABCDHomework1.4第1题单选题(2分)1-4______referstotheprocessofheating,heatpreservationandcoolingthemetalinthesolidstateinanappropriatewaytoobtaintheexpectedstructureandperformance.AColdtreatmentBheattreatmentCHotworkingDColdworking第2题单选题(2分)1-4Heatthesteelpartsto30-50℃aboveAC3orACCM˚C.Theheattreatmentofuniformcoolinginfreeflowingairafterproperheatpreservationtimeiscalled_____.AnormalizingBannealingCtemperingDquenching第3题单选题(2分)1-4Thenormalizedcoolingrateislarge,theundercoolingdegreeislarge,andthepearlitestructureobtainedislargeandrelativelysmall,so____alsohigher.APlasticityandhardnessBStrengthandhardnessCfatiguestrengthDStrengthandplasticity第4题多选题(2分)1-4Thethreeelementsofheattreatmentinclude.()AheatingtemperatureBHoldingtimeCCoolingrateDBoilingtime正确答案：ABC第5题多选题(2分)1-4Whyheatpreservationisnecessaryformetalheattreatment?()ATheworkpieceshallbeheatedevenlyandthestructuretransformationshallbefullycarriedoutBItismoreimportanttoobtainaustenitewithuniformcomposition,soastoobtainidealstructureandpropertiesaftercoolingCPlentyoftimeDimproveworkefficiency正确答案：ABHomework1.5第1题单选题(2分)1-5Steelcanbedividedintononalloysteel,lowalloysteeland__。AHighalloysteelBalloysteelCcarbonsteel第2题单选题(2分)1-5Thecarboncontentofhighqualitycarbonstructuralsteel08is____。A0.80%B0.08%C8%D0.01%第3题单选题(2分)1-5Steelforultra-highstrengthshipsandoffshorestructuresshallbe__statusfordeliveryAannealingBnormalizingCquenchingDquenchedandtempered第4题单选题(2分)1-5Ashullstructuralsteel,high-strengthshipandmarinestructuralsteelshouldhaveexcellentprocessingand__performance.AforgingBcastingCweldingDimpact第5题多选题(2分)1-5Specialperformancesteelsforhullinclude________、________________。()AStainlesssteelBLowtemperaturesteelCCladsteelplateDCorrosionresistantsteel正确答案：ABCHomework1.6第1题单选题(2分)1-6Graycastirongraphite__Shapearrangement.AReticularBglobularCschistoseDacicular第2题单选题(2分)1-6Nodularcastirongraphite__Shapearrangement.AReticularBschistoseCglobularDacicular第3题单选题(2分)1-6Use__toindicatethegradeofgreycastiron.AHTBHZTCHKZTDHTZ第4题多选题(2分)1-6Duetotheexistenceofgraphite,castironhassomepropertiesthatcarbonsteeldoesnothave?()AGoodwearresistanceBShockabsorptionCLownotchsensitivityDExcellentmachinability正确答案：ABCD第5题多选题(2分)1-6Whatcancopperalloysbedividedintoaccordingtotheirchemicalcomposition?()AbronzeBRedcopperCbrassDcopper-nickel正确答案：ACDHomework2.1第1题单选题(2分)2-1Weldingisakindofprocessingmethodthatmakestheweldmentsreachthe______byheatingorpressurizing,orboth,andwithorwithoutfillermaterials.AatomiclevelBMolecularlevelCprotonslevelDQuantumlevel第2题单选题(2分)2-1Arcistheweldingheatsourceofarcwelding,andthechargedparticlespassbetweentwoelectrodes______Aconductiveprocessinspace.AgasBsolidCliquid第3题多选题(2分)2-1Gasionizationisdividedinto____、_____andphotoionization。AParticleionizationBthermalionizationCFieldionizationDLaserionization正确答案：BC第4题多选题(2分)2-1Whichareasarethestructureofweldingarcdividedinto?()ACathodeareaBAnodeareaCArccolumnarea正确答案：ABC第5题多选题(2分)2-1Themainformsofdroplettransferduringmetalarcweldingareasfollows:()AContacttransitionBFreetransitionCSlagwalltransitionDNaturaltransition正确答案：ABCHomework2.2第1题单选题(2分)2-2Meltingefficiency:usedtomeltmetalduringwelding______Percentageofheatsourcepower。AintensityBweightCHeatDtemperature第2题单选题(2分)2-2Duringfusionwelding,locallymelted______Thepercentageintheweldmetaliscalledthefusionratio。AWeldingrodBBasemetalCWeldingwireDWeldment第3题多选题(2分)2-2Whatarethefactorsaffectingthefusionratio()AWhentheweldingcurrentincreases,thefusionratioincreases;BWhenthearcvoltageorweldingspeedincreases,thefusionratiodecreases。CFormulti-layerwelding,thefusionratiograduallydecreaseswiththeincreaseofthenumberofweldbeadlayers.DWithdifferentgrooveforms,thedownwardtrendisdifferent.Thesurfacesurfacingdecreasesthefastest;V-groovetakesthesecondplace;ThereductionofU-grooveistheleast.正确答案：ABCD第4题判断题(2分)2-2Thelengthofmoltenpoolisproportionaltothearcenergy.()第5题判断题(2分)2-2Themovingstateoftheweldpool.Theliquidmetalintheweldpoolisnotstatic,butisstronglymoving.()Homework2.3第1题单选题(2分)2-3Thehigherthecrystallizationrate,thebetterthethermalconductivityofthemetal.Thehighertheviscosityoftheliquidmetal,thesmallerthedensityoftheliquidmetal,andtheeasieritistoproduce______.AcrackBInclusionCstomaDsplash第2题多选题(2分)2-3Wheredoeshydrogenmainlycomefrom?()AOrganicmatterinelectrodecoatingandfluxBCrystallizedwateroradsorbedwaterCOilstainonthesurfaceofbasemetalandweldingrodDRustandmoistureintheair正确答案：ABCD第3题多选题(2分)2-3Whataretheeffects()ofhydrogenonweldqualityduringwelding()ACausehydrogenembrittlementBProducewhitespotsCFormingporesDColdcrack正确答案：ABCD第4题判断题(2分)2-3Themosteffectiveandpracticalwaytoreducetheharmofnitrogenistostrengthenmechanicalprotection.()第5题判断题(2分)2-3Whenairenterstheweldingarea,itismostlikelytoproducenitrogenpores.()Homework2.4第1题单选题(2分)2-4Whenthecomponentisheatedunevenly,aslongasthetemperatureishigherthantheyieldpointofthematerial,thecomponentwillproducecompressiveplasticdeformation.Aftercooling,thecomponentwillhave______Andresidualdeformation.AResidualstressBstressCdeformationDbend第2题单选题(2分)2-4_____oftenoccursintheweldingprocessofthinplateswiththicknesslessthan6mm,whichisalsocalledinstabilitydeformation.AWavedeformationBAngulardeformationCShrinkagedeformationDBendingdeformation第3题多选题(2分)2-4Whatarethecausesofweldingstressanddeformation?()ANon-uniformheatedBShrinkageofweldmetalCChangeofmetalstructureDRigidityandrestraintofWeldments正确答案：ABCD第4题判断题(2分)2-4Afterwelding,theweldzoneisusuallytensilestress.()第5题判断题(2分)2-4Thermalstress:thestresscausedbytheinconsistentthermalexpansionofeachpartoftheweldmentduetounevenheatingduringwelding.()Homework2.5第1题单选题(2分)2-5Generally,thedeformationdirectionoftheweldmentduringweldingandthedeformationdirectionoftheweldmentafterwelding_______.AidenticalBcontraryCunanimousDNotfixed第2题多选题(2分)2-5Whataretheeffectsofweldingresidualstressesonweldedstructures?()AInfluenceonstructuralstrengthBInfluenceondimensionaccuracyofcomponentmachiningCInfluenceonthestabilityofcompressionmembersDEffectonstresscorrosioncracking正确答案：ABCD第3题多选题(2分)2-5Whatarethemethodstoeliminateweldingresidualstress?()AHeattreatmentmethodBMechanicalstretchingmethodCTemperaturedifferencestretchingmethodDhammertheweldedseam正确答案：ABCD第4题多选题(2分)2-5Whatarethedesignmeasurestoreduceweldingresidualstress?()AMinimizethenumberandsizeofweldsonthestructureBAvoidexcessiveconcentrationofwelds,andkeepsufficientdistancebetweenweldsCAdoptthejointformwithlessrigidity正确答案：ABC第5题多选题(2分)2-5Whatarethetechnologicalmeasurestoreduceweldingresidualstress?()AAdoptreasonableassemblyweldingsequenceanddirectionBPreheatingmethodCReduceweldrestraintDHeating"stressreliefzone"method正确答案：ABCDHomework2.6第1题单选题(2分)2-6Thewaysofflameheatingincludepointheating,linearheatingand____.ACircleheatingBSheetheatingCTriangleheatingDZigzagheating第2题多选题(2分)2-6Whatarethetypesofweldingdeformationbesidesangulardeformation?()AShrinkagedeformationBBendingdeformationCWavedeformationDTwistdeformation正确答案：ABCD第3题多选题(2分)2-6Whataretheprocessmeasurestocontrolweldingdeformation?()AAllowancemethodBInversedeformationmethodCRigidfixationmethodDSelectreasonableassemblyandweldingsequenceEReasonableselectionofweldingmethodsandweldingprocessparameters正确答案：ABCDE第4题多选题(2分)2-6Whatarethemethodsforcorrectingweldingresidualdeformation?()AManualcorrectionBMechanicalcorrectionCFlameheatingcorrectionDRewelding正确答案：ABC第5题判断题(2分)2-6Allowancemethod:whenblanking,thelengthorwidthofthepartshallbeappropriatelyincreasedcomparedwiththedesignsizetocompensatefortheshrinkageoftheweldment.()Homework3.1第1题单选题(2分)3-1Whatarethebasicoperatingtechniquesofshieldedmetalarcwelding()AArcstrikingandstriptransportationBConnectionandclosureofweldsCArcstriking,striptransportation,weldconnectionandendingDArcstriking,striptransportationandslagstriking第2题多选题(2分)3-1Whatarethecharacteristicsofshieldedmetalarcwelding?()ASimpleequipmentandconvenientmaintenanceBFlexibleoperationandwideapplicationrangeCHighrequirementsforweldersDLowproductionefficiencyandpoorworkingconditions正确答案：ABCD第3题多选题(2分)3-1Whatarethetypesofweldingjointsforshieldedmetalarcwelding()AButtjointBT-jointCAnglejointDLapjointETerminationjoint正确答案：ABCDE第4题多选题(2分)3-1Whenthearcisignited,whichdirectionsshouldtheweldingrodmove?()AFeedingofweldingrodtomoltenpoolBElectrodemovesalongtheweldingdirectionCLateralswingofweldingrod正确答案：ABC第5题判断题(2分)3-1Intheweldingprocess,thegeneralnameofvariousactionsmadebytheweldingrodrelativetotheweldiscalledstriptransportation.()Homework3.2第1题单选题(2分)3-2Submergedarcweldingisamethodofweldinginwhichthearcburns__AInthefluxlayerBUnderfluxlayerCInslagDInweldingslag第2题单选题(2分)3-2WhensubmergedarcweldingisusedtoweldthefilletweldofT-jointorlapjoint,twomethodsareusuallyused:__andtransversefilletwelding。AfilletweldingintheflatpositionBfilletweldinginverticalpositionCTransverseshipweldingDfilletwelding第3题多选题(2分)3-2Whataretheadvantagesofsubmergedarcwelding?()AHighproductivityBGoodweldqualityCLowweldingcostDGoodworkingconditions正确答案：ABCD第4题多选题(2分)3-2Whatarethedisadvantagesofsubmergedarcwelding()AItismainlyapplicabletotheweldingofweldsathorizontalpositionBItcannotbeusedtoweldmetalmaterialsthatarepronetooxidationCOnlyapplicabletoweldingofmediumandheavyplatesDSubmergedarcweldingisonlyapplicabletotheweldingoflongstraightwelds正确答案：ABCD第5题判断题(2分)3-2SincethemaincomponentsofthefluxusedinsubmergedarcweldingareSiO2,MnO,etc.,itcannotbeusedtoweldmetalmaterialsthatarepronetooxidation.()Homework3.3第1题单选题(2分)3-3TheextensionlengthofweldingwireforCO2gasshieldedweldingdependsonthediameterofweldingwire.Generally,theextensionlengthofweldingwireisabout____timesofthediameterofweldingwireanddoesnotexceed15mm.A10B20C30D40第2题多选题(2分)3-3WhatarethecharacteristicsofCO2gasshieldedwelding()AHighproductionefficiencyandenergysavingBLowweldingcostCSmallweldingdeformationDEasytooperateandmaster正确答案：ABCD第3题多选题(2分)3-3Whataretheprocessparametersforshort-circuittransitionofCO2gasshieldedwelding?()AArcvoltageandweldingcurrent.BWeldingcircuitinductanceandweldingspeedCDiameterandextensionlengthofweldingwireDtheflowrateofgas正确答案：ABCD第4题判断题(2分)3-3Comparedwiththegeneralarcwelding,thesplashofCO2gasshieldedweldingismoreserious.()第5题判断题(2分)3-3ThewholecoilofweldingwireisusedforCO2welding,sotheweldingroddoesnotneedtobereplacedduringtheweldingprocess,avoidingthewasteofweldingrodhead.()Homework4.1第1题单选题(2分)4-1Whataretheinternaldefectsofwelding?()ASlaginclusionandincompletepenetrationBUndercutandoverlapCCraterandsurfaceairholeDsurfacecrack第2题单选题(2分)4-1Surfacecracksduetoimproperselectionofweldingparametersorincorrectoperationprocess,groovesordepressionsalongthebasemetalattheweldtoearecalled__。AblowholeBUndercutCoverlapDIncompletepenetration第3题多选题(2分)4-1Whichofthefollowingweldinspectionsarenon-destructive?()ARadiographicinspectionBUltrasonicflawdetectionCPenetranttestingDMagneticparticleinspection正确答案：ABCD第4题多选题(2分)4-1Whichofthefollowingdefectsisnotallowedontheweldsurface?()AcrackBoverlapCLackoffusionDIncompletepenetration正确答案：AC第5题判断题(2分)4-1Measurementoffilletweldthickness:whenmeasuringthethicknessoffilletweld,theworkingfaceofthemainrulershallbeclosetotheweldment,andtheslidingheightrulershallbeincontactwiththeweld.Thevalueindicatedbytheheightruleristhethicknessoffilletweld.()Homework4.2第1题单选题(2分)4-2()isthemostimportantindexforevaluatingradiographicquality,whichmarkstheabilitytofinddefectsinradiographicinspection.AImagequalityindicatorBsensitivityCBlacknessvalue第2题多选题(2分)4-2WhatarethepropertiesofX-raysrelatedtoflawdetection?()AinvisibleandtravelinastraightlineatthespeedoflightBUnchargedandunaffectedbyelectricandmagneticfieldsCtheabilitytopenetratesubstancesthatcannotbepenetratedbyvisiblelight,suchasbonesandmetals,andhaveattenuationcharacteristicsinsubstancesDionizesubstances,sensitizefilms,andmakecertainsubstancesfluorescent正确答案：ABCD第3题多选题(2分)4-2Whatarethebasiccomponentsofthedetectionsystem?()ARaysource,leaddiaphragm,filterplateBBottomleadplateandstandardbeltCLeadshutter,workpieceDCassette,film,intensifyingscreen正确答案：ABCD第4题判断题(2分)4-2Radiographicinspectionisanon-destructiveflawdetectionmethodthatusestheX-rayorγraytopenetratethematerialandthepropertyofattenuationinthematerialtofindtheinternaldefectsofthematerial.()第5题判断题(2分)4-2Filmevaluationistoobservethenegativefilmthroughthefilmviewinglamp,determinethequalitative,quantitativeandpositioningofthedefectsonthenegativefilmthroughtheimageonthenegativefilm,evaluatethequalitygradeoftheworkpieceaccordingtothestandard,andwritetheinspectionreport.()Homework4.3第1题单选题(2分)4-3Ultrasonictestinganondestructivetestingmethodwhichusesthepropagation,reflectionand__AndotherphysicalpropertiesofultrasonictofinddefectsAreceiveBattenuationCspreadDReflexion第2题单选题(2分)4-3Ultrasonictestingequipmentisgenerallycomposedofultrasonicflawdetector,probeand__。AwaferBTestblockCTestpieceDIronblock第3题多选题(2分)4-3Thecommonlyusedprobesforultrasonictestingare__、__and__。AStraightprobeBAngleprobeCSinglecrystalprobeDDoublecrystalprobe正确答案：ABD第4题判断题(2分)4-3Theultrasonicdetectoristhemainequipmentfortesting.Itsmainfunctionistogeneratehigh-frequencyelectricoscillationanduseittostimulatetheprobetoemitultrasonicwaves.()第5题判断题(2分)4-3Accordingtodifferentpurposesandrequirements,testblocksaregenerallydividedintothefollowingtwocategories:standardtestblocksandreferencetestblocks.()Homework4.4第1题单选题(2分)4-4Magneticparticletestinguses__todetectdefectsinmaterialsandworkpieces。AMagnetphenomenonBMagneticfieldphenomenonCAdsorptionphenomenonDMagneticfluxleakagephenomenon第2题单选题(2分)4-4Thesolutionformedbymixingmagneticpowderandliquidinacertainproportioniscalled__。AGeneralmagneticparticleBNonfluorescentmagneticparticleCMagneticsuspensionDGeneralmagneticsuspension第3题判断题(2分)4-4Magneticparticletestingcannotdetectnon-magneticmaterialssuchascopper,aluminum,magnesiumandtitanium()第4题判断题(2分)4-4Magneticparticletestingisapplicabletothetestingofdiscontinuitiesonthesurfaceandnearsurfaceofferromagneticmaterialswithsmallsize,extremelynarrowgap(suchas0.1mmlongandmicronwidecracks)anddifficulttobeseenvisually.()第5题判断题(2分)4-4Magneticparticletestingcandetectmartensiticstainlesssteelandprecipitationhardeningstainlesssteel()Homework4.5第1题单选题(2分)4-5Penetranttesting()isanon-destructivetestingmethodbasedon_____principletoinspectthesurfaceopeningdefectsofnonporousmaterials.AresponseBphotosynthesisCcapillaryactionDAdsorptionprinciple第2题单选题(2分)4-5Intheadsorptionprinciplepenetranttesting,whentheambienttemperatureis5-50℃,thepenetrationtimeusuallyneeds_____minute.A10-15minB15-20minC10minD15min第3题判断题(2分)4-5Penetranttestingisanon-destructivetestingmethodbasedontheprincipleofcapillaryactiontoinspectthesurfaceopeningdefectsofnonporousmaterials.()第4题判断题(2分)4-5Penetranttestingisapplicabletothequalityinspectionofsurfaceopeningdefectsofvariousmetalmaterialsornon-metalmaterials.()第5题判断题(2分)4-5Penetranttestingisanon-destructivetestingmethodthatusesthepenetrantwithfluorescentdye(fluorescencemethod)orreddye(coloringmethod)toshowdefecttraces.()Homework5.1第1题单选题(3分)5-1Whentheweldingrodarcweldingplateisbuttweldedhorizontally,thebottomlayershallbeappliedby____.AContinuousweldingBTackweldingCBreakarcwelding第2题单选题(3分)5-1Thereversedeformationis()degreesduringtheassemblyofweldingrodarcweldingplatebuttweldingworkpiece.A2-3B2-4C2-5第3题单选题(4分)5-1The___methodshallbeadopted,andnoswingshallbemadeduringtheweldingprocessuntileachelectrodeiswelded.AsawtoothstripBcirclestripCstraightlinestripHomework5.2第1题单选题(3分)5-2Whentheweldingrodarcweldingplateisbuttweldedvertically,thefillinglayerandcoveringlayershalladoptthe____transportationmethod.AsawtoothstripBcirclestripCstraightlinestrip第2题单选题(3分)5-2Duringverticalbuttweldingofelectrodearcweldingplate,stopattheedgeoftheweldtoprevent().AoverlapBUndercutCIncompletepenetrationDLackoffusion第3题单选题(4分)5-2Forverticalbuttweldingofelectrodearcweldingplate,theweldingslagofthebottomlayerandfillinglayershallbe().AproperremovedBcompletelyremovedCkeptHomework5.3第1题单选题(3分)5-3()shallbestrictlyadoptedduringoverheadbuttweldingofelectrodearcweldingplateALongarcweldingBShortarcweldingCShortarcweldingandlongarcwelding第2题单选题(3分)5-3Duringbuttoverheadweldingoflongarcweldingrodandarcweldingplate,thedropletshallbepushedupwardbythe____oftheweldingrod.AarcblowingforceBDropletblastingforceCElectromagneticforce第3题单选题(4分)5-3Duringoverheadbuttweldingofelectrodearcweldingplate,themoltenmetalinthedropletandpooliseasytoflowdownundertheactionofgravity,itwillcause____.AoverlapBUndercutCcrackDIncompletepenetrationHomework5.4第1题单选题(3分)5-4Duringsubmergedarcwelding,inordertopreventthedeviationofweldbead,adjustthe____oftrolleyweldingwire.AalignmentBangleClength第2题单选题(3分)5-4Thesubmergedarcweldingfluxmustbecoveredevenlyduringtheweldingprocess,andthe____shallnotbeexposed.AsolderwireBSolderingSeamCarclight第3题单选题(4分)5-4Theslagshellmustberemovedaftereachlayerofweldbeadisweldedbysubmergedarcwelding,andthefluxshallbe____.AthrownawayBrecoveredCclearedHomework5.5第1题单选题(3分)5-5ForCO2gasshieldedwelding,itisbettertocutoffasectionofweldingwireattheendbefore____.AweldingBarcstrikingCarcbreaking第2题单选题(3分)5-5DuringtheflatweldingofCO2gasshieldedwelding,theworkpiecesurfaceatthearcstrikingpositionshallbe____.AleveledBpreheatedCCleanedup第3题单选题(4分)5-5DuringtheflatweldingofCO2gasshieldedwelding,theheightofthenozzleshallbekepttoprevent____.AIncompletepenetrationBUndercutCoverlapDLackoffusionHomework5.6第1题单选题(3分)5-6InthehorizontalweldingofCO2gasshieldedwelding,lowcurrentandshortarcweldingareadoptedforthebackinglayertoprevent____.ABurningthroughBIncompletepenetratio