电子科技大学硕士研究生英语分级测验考试PlacementTest带答案

PlacementTestforGraduateStudentsAugust,20151.本分级测试主要检测学生英语水平、语言能力和批判性思维能力，为英语教学分班提供依据，望同学们认真答题，体现出自己真实水平。2.本测试同时也为教师教学提供参考，测试成绩按一定比例计入平时成绩。3.本测试时长共90分钟。测试对速度有一定要求，同学们可参考各部分建议，合理分配答题时间。4.第1~30题为听力，请用耳机收听。5.所有答案做在机读卡上。6.试卷请妥善保管，开学第一周带到课堂。PARTILISTENINGCOMPREHENSION(30minutes,30points,1pointeach)SectionADirections:Inthissection,youwillhear9shortconversationsbetweentwospeakers.Attheendofeachconversation,aquestionwillbeaskedaboutwhatwassaid.Theconversationsandthequestionswillbereadonlyonce.ChoosethebestanswerfromthefourchoicesgivenbymarkingthecorrespondingletterwithasinglebaracrossthesquarebracketsonyourmachinescoredAnswerSheet.1.A.Itwaswet.B.Itwastorn.C.Itwasdirtywithdust.D.Itwasblood-stained.2.A.Doctorscandonothingabouthisproblem.B.Itistoosmallaproblemtogettreated.C.Healthcareisveryexpensive.D.Doctorscanfixhisproblem.3.A.Smokingisstupid.B.Smokingonecigaretteisenough.C.Smokinginpublicplacesisoffensive.D.Smokingiscool.4.A.Rememberthisplace.B.Moveaheadwiththeline.C.Answerthecall.D.Comebackquickly.5.A.Hedoesn’tdrinkteaveryoften.B.HeisnotinterestedinPekingopera.C.HeknowsnothingaboutPekingopera.D.HeenjoyswatchingPekingopera.6.A.885-450-4310B.848-405-3140C.858-405-3410D.405-858-34107.A.She’llhelpthemanoutofthetrouble.B.Themanhasalwaysbeenintrouble.C.Nooneelsewillhelpthemanexceptherself.D.Shedoesn’twanttheirrelationsmentioned.8.A.Johnwillnotstayinjailforalongtime.B.Johnisafamilymemberwithabadreputation.C.Johnhasbeendrivenoutofthefamily.D.John’sjobdiffersfromthatofhisfamilymembers.9.A.Shedislikesthesmellinthehouse.B.Shesmellssomethingburn.C.Sheisafraidthatthehouseisonfire.D.Shefeelssomethingiswrong.SectionBDirections:Inthissection,youwillhear3conversations.Attheendofeachconversation,questionswillbeaskedaboutwhatwassaid.Theconversationsandthequestionswillbespokenonlyonce.ChoosethebestanswerfromthefourchoicesgivenbymarkingthecorrespondingletterwithasinglebaracrossthesquarebracketsonyourmachinescoredAnswerSheet.ConversationOneQuestions10to14arebasedontheconversationyouhavejustheard.10.Whatisthepurposeoftheconversation?A．Thewomanwantstomakeanappointmentwiththelibrarian.B．Thewomanistryingtoreserveabookforherclassmate.C．Thewomanisinquiringabouttheavailabilityofstudyrooms.D．Thewomanwantstoreserveadifferentroominthelibrary.11.Listenagaintopartoftheconversation.Thenanswerthequestion.Whydoesthemansaythis:A．ToinformthewomanthatnoroomsareavailableB．ToencouragethewomantoreservearoomnowC．TorecommendtheroomsonthethirdfloorD．Toletthewomanknowwhichroomsarebetter12.Accordingtotheman,whyaresofewstudyroomsavailable?A．Therearemorestudentsnowthaninthepreviousyear.B．Severalroomsarebeingusedasofficesforlibrarystaff.C．Thereisaproblemwithstudentsreservingmorethanoneroom.D．Someoftheuniversitybuildingsarestillunderconstruction.13.Whydoesthewomanneedastudyroom?A．Sheispreparingforafinalexamination.B．Herprofessorrequireseveryonetohaveastudyroom.C．Shedoesnothavespacetostudyinherapartment.D．Sheneedsaplacetomeetwithotherstudents.14.Whydoesthemansaythis:A．TotellthewomanaboutthebuildingthatheworksinB．TopersuadethewomantoacceptaroominanotherbuildingC．TodescribeaninterestingaspectoftheuniversitylayoutD．TodirectthewomantosomeoneelsewhocanhelpherConversationTwoQuestions15to19arebasedonthepassageyouhavejustheard.15.Whatarethestudentsmainlydiscussing?A．HowmusicdiffersfromnoiseB．SoundsmadebymusicalinstrumentsC．ThemethodstoproduceantinoiseD．Whysomesoundsareunpleasant16.Accordingtotheconversation,whatisnoise?A．ThecompleteabsenceofsoundB．PatternsproducedbysoundsinnatureC．RandomsoundwithirregularwavesD．Soundsmadebyacomputervoice17.Listenagaintopartoftheconversation.Thenanswerthequestion.Selectthesentencethatbestexpresseshowthewomanprobablyfeels.A．"I'mfrustratedbecauseIdon'tunderstand."B．"I'mgladthatyouknowsomuchaboutmusic."C．"Idon'tagreewithwhatyouaresaying."D．"IwishthatIknewhowtoplaythedrums.”18.Howdoesthemanhelpthewomanunderstandthemeaningof"antinoise"?A．Bycontrastingmusicandantinoise.B．Byreadingadefinitionfromthetextbook.C．Bydescribingthesoundofadrumbeat.D．Bytellingheraboutacomputerprogram.19.Whatwillthewomanprobablydo?A．Dropoutofthemusictheoryclass.B．Listentorecordingsofvariousinstruments.C．Readthetextbookbeforethenextlecture.D．Useacomputertosearchforinformation.ConversationThreeQuestions20to24arebasedontheconversationyouhavejustheard.20.Whyistheclassdiscussingthetechnicalrequirementsofmurals（壁画）?A．Theyarepreparingforanexamination.B．Theyplantovisitsomefamousmurals.C．Theyarehelpingtodesignanewbuilding.D．Theywillbecreatingtheirownmural.21.Accordingtothediscussion,whatfactorsshouldbeconsideredinplanningamural?A．Thepositionoftheobserver.B．Thecharacteroftheartist.C．Thedistancefromthelobbytotheelevator.D．Thecolorsofthepaint.22.Whatdoestheinstructormeanwhenshesaysthis:A．Abuildingwithamuralwillattractalotofvisitors.B．Amuralservesthesamepurposeasotherformsofart.C．Theterm"mural"hasseveraldifferentmeanings.D．Amuralisanexpressionofthebuilding'scharacter.23.Whatisthepurposeofhavinganairspacebetweentheouterwallandtheplaster?A．Itwillprotecttheplasterfromtemperaturechanges.B．Itwillgivethemuralagreatersenseofdepth.C．Itwillreducethetimeneededfordryingtheplaster.D．Itwilleliminatetheneedtowashthewallfrequently.24.Whydoestheinstructorsaythis?A．ToexplainhowawallcanbemadestrongerB．TodescribetheprocessofframingamuralC．ToexplainhowtocreateaninsulatingairspaceD．TodescribeatechniquefortexturingaplasterwallSectionCDirections:Inthissection,youwillhearashortlecture.Aftertherecording,questionswillbeaskedaboutwhatwassaid.ChoosethebestanswerfromthefourchoicesgivenbymarkingthecorrespondingletterwithasinglebaracrossthesquarebracketsonyourmachinescoredAnswerSheet.Questions25to30arebasedonthelectureyouhavejustheard.25.Howdoestheprofessordevelopthetopicofpoliticalparties?A．BycomparingthegoalsofdifferentpartiesB．BypromotingtheviewsofaspecificpartyC．Bydescribingpartiesinatwo-partysystemD．Byexplaininghowtoorganizeaparty26.Listenagaintopartofthelecture．Thenanswerthequestion.Whydoestheprofessorsaythis:A．Totestthestudents'knowledgeofpartiesB．TofindoutwhichpartythestudentssupportC．TointroduceapointthathewillmakeD．Toshowthatallstateshaveatwo-partysystem27.Listenagaintopartofthelecture．Thenanswerthequestion．Whatdoestheprofessorimplyaboutpoliticalparties?A．Partiesmakedecisionsbasedontheinterestsofseveralorganizations．B．Partiescanneveraccomplisheverythingthattheywouldliketodo．C．Partiescarryontheirworkthroughtheeffortsofunpaidvolunteers．D．Partiesarenecessaryintheexerciseofdemocracyinnationalstates．28.Basedontheinformationinthelecture,answerthequestion:WhichofthefollowingstatementsisNOTtrueaboutpoliticalparties?A.Theyareagroupofpeoplewhocometogethermainlyforamusement.B.Theyorganizevotersandcompeteforsupportonmajorissues.C.Theyarevoluntaryorganizationsofpeoplewhoagreeonpublicpolicies.D.Theyhaveresearchofficesthatdeveloppositionsonimportantissues.29.Whatdoestheprofessormeanwhenhesaysthis:A．Itispossibletoenjoypoliticsbutdislikegovernmentatthesametime.B．Apoliticalpartycaresaboutmajorissues,butagovernmentdoesn'tcare.C．Politicsisaboutcompetition,whilegovernmentisaboutresponsibility.D．Electionsandgovernmentareliketwosidesofthesamecoin.30.Whydoestheprofessorsaythis:A．Toshowhowmajorpartiesusuallydealwiththesameissues.B．Tosuggestthatbothpartiesshouldgiveeducationmoreattention.C．Tocontrastthephilosophyandmethodsofopposingparties.D．Topointoutwhichpartyismoreconcernedwitheducation.PARTIIGrammar(10minutes,10points,1pointeach)Directions:Therearetensentencesinthissection.Readeachsentencecarefully.Ifthereisanerror,selecttheunderlinedpartthatisincorrect.Ifthereisnoerror,chooseanswerD.Markthecorrespondingletterwithasinglebaracrossthesquarebracketsonyourmachine-scoringAnswerSheet.　31.Thepresenceofstrongfeeling,thecauseofwhich(A)isnotfullyunderstood,alwayshastheeffect(B)ofmakingwe(C)humanbeingsuneasy.Noerror(D)32.Idonotwishtomake(A)aformalcomplaint,butIwouldhavebeenbetterpleasedifyougave(B)theawardtothepersonwho(C)bestdeservedit.Noerror(D)33.Thetribesmenmadeofferingstoplacate(A)thegods,whom(B)theybelieved,were(C)angrywiththem.Noerror．(D)34.Fromancienttimes(A),sculpturehadbeen(B)　consideredtheprerogativeofmen,andevennow,insomepartsoftheworld,womensculptorsface(C)hostilityandsuspicion.Noerror(Ｄ)35.AccordingtoHume,itisnotlogicandreasoningthat(A)determine(B)ouractions,but　(C)emotion.Noerror.　(D)36.Thegeneralreportedthat(A),asaresultof(B)　financialconstraints,less(C)soldierswouldbesentonpeace-keepingmissionsthisyear.Noerror.（D）37.Theornatepillarsandlife-size（A）statuesthatthemagnatehaschosen(B)toadornhisswimmingpoolarelikeaGreektemple(C).Noerror.(D)38.Afteryouhavewritten(A)adefinitioninyourvocabularynotebook,addafew(B)waystousethewordorasentencetoillustrateit's(C)meaning.Noerror.(D)39.Theracingchampionhad（Ａ）madenomention（Ｂ）inhisspeechofthemechanicsonwhom（Ｃ）hissuccesshaddepended.Noerror.（Ｄ）40.Thenewlawistoo（Ａ）stringent;itwillbe　（Ｂ）neitherrespectedor（Ｃ）obeyed.Noerror.（Ｄ）PARTIIICriticalReading(50minutes,30points,1pointeach)Directions:Choosethebestanswerfromthefourchoicesgivenandmarkthecorrespondingletterwithasinglebaracrossthesquarebracketsonyourmachine-scoringAnswerSheet.1Whilevirtuallyallscientistsaccepttheprinciplesofevolutionarytheory,thereremainsgreatuncertaintyconcerningthemechanismofrapidanddrasticchangebetweensuccessivespecies.Inthepast,interspecieshybridizationwasdismissedasapossiblesolution,sincehybridsarerarelyasvigorousaspurebredspecies.However,currentresearchonhybridizationsuggeststhatalthoughsomehybridsarenotasvirileaseitheroftheparentspecies,theyareoftenstrongenoughtopasstheirtraitson.Scientistshavealsofoundhybridspecies,suchascertaintypesofcorn,thatarestrongerthantheirparentspecies,aphenomenonknownas“hybridvigor”.Thesefindingssuggestthathybridizationplaysafarmoreimportantroleinevolutionthanpreviouslysuspected.41.Itcanbeinferredthatsomescientistspreviouslybelievedthat________.A.thedetailsofevolutionarytheorymayneverbefullyunderstoodB.hybridplantslacktheabilitytoreproducebythemselvesC.plantsthatarerobustpossessanevolutionaryadvantageD.purebredplantsplayarelativelyminorroleinevolution42.Thepassageimpliesthatmostscientistswilladoptatheorythat________.A.includeselementsaboutwhichlittleisknownB.cannotbeprovenbyexperimentalmeansC.involvesideaswhichwilllikelybedisprovedlaterD.haslimitedreal-worldapplications2Thoughmostpeopleknowthedefinitionoftheword“boycott”,fewknowitsorigin.NamedforCaptainCharlesBoycott,thewordasweknowitoweslesstohimthantoIrishnationalistCharlesParnell.ParnellorganizedIrishfarmersandconvincedthemtofixtheirrentrates.WhenBoycottrefused,Parnellunleashedthepowerofthepeople.AbandofhostilepeasantsforcedtheCaptain’sservantstoleave.Therewerenolaborerstogathertheharvestandnostablementocarefortheanimals.Boycottwasnotallowedtoenterstoresormakepurchases.Eventually,BoycottandhiswifefledIreland,andParnellwashailedastheworkingman’shero.43.Thepassageisbestsummarizedbywhichofthefollowing?A.Theoriginofawordisexplored,andanexplanationforitspopularityisgiven.B.Awordisintroduced,andahistoryofitsusageisrelated.C.Aneventisdescribedasthereasonbehindashiftinaword’smeaningD.Awordisintroduced,andthehistoryofitscoiningisrelated.44.Itcanbemostreasonablyinferredfromthepassagethat_______.A.Boycott’slandwasnotharvestedthatyearB.thetownspeoplereferredtoweresympathetictothefarmersC.ParnellwaspopularamongallIrishmenD.thefarmersthreatenedBoycottwithphysicalharm3Passage1:NomajorpoliticalelectionintheUnitedStateshaseverbeendecidedbyonevote.Infact,asinglevotecontributesonlyaboutonemillionthofthetotalresultoftheaveragestatewideelection.Consideringhownumericallyinsignificantasinglevoteis,isthereanyrationaljustificationforanindividualtovote?Inordertoanswerthisquestion,onemustlookpastthemerenumericalvalueofavote.Anindividual’svoteisvaluableasameasureofthatindividual’sbeliefinthesystemofgovernment,whichlikewiseindicatesthedegreetowhichapersonfeelsincludedinthegreatersocialorder.Passage2:Whenrecentlyaskedwhomhevotedforinthelastpresidentialelection,afriendofminereplied,“Ididn’tbother.”Witharatherboredshrug,andlittleembarrassment,myfriendcontinued,“It’snotlikeitmatters.Myvotewouldn’thavechangedtheoutcome.”Icouldn’thelpthinkingthenthattheargumentwasuncannilypersuasive.IfIhadstayedinbedthatmorning,theresultwouldlikewisebeexactlythesame.Buttheargumentdoesnotholdupunderscrutiny.Ifdemocracymeansrulebythepeople,andnotbyanyoneindividual,thenwhyshouldthevoteofjustonepersondeterminetheoutcomeofanelection?Noperson,nomatterwhoheis,shouldbeabletochangethegreaterwillofacollectedgroup.Theideaofdoingsoissimplyundemocratic.45.Whichofthefollowing,iftrue,wouldmoststrengthenthehypothesisoftheauthorofPassage1concerningvotingbehavior?A.Historicaldocumentsrevealthatmaylocalelectionshavebeendecidedbyasinglevote.B．AnewstudyfindsthatmanyAmericansfeelthatvotingisaburdensomeinconvenience.C．ApollofAmericancitizensindicatesthatmostcitizensconsidervotinganimportantcommunalduty.D．Votingrecordsshowthatmostpeoplewhovoteparticipateinbothnationalandlocalelections.46.TheauthorofPassage1wouldmostlikelyconcludewhichofthefollowingaboutthe“friend”describedinPassage2?A.Thefriendlikelyfeelsthatheisdisconnectedfromthesocietyinwhichhelives.B．Unlesshechangestheoutcomeofanelection,thefriendisunlikelytoevervote.C.Thenumberofpeopletodaywhoactasthefrienddoesindicatesafundamentalflawinsociety.D．Peoplewhodon’tfeeltheneedtovotearegenerallysatisfiedwithlifeasitis.47.Bothpassagesservetodiscouragethe________.A．inclinationofAmericanstoinventexcusesfornotvotingB．tendencyofvoterstoavoidmakingdifficultdecisionsC．valuationofavotebyitsabilitytodecideanelectionD．apathythatsomevotersfeelaboutthelackofrealchoices48.ThefinalsentenceofPassage2servesto________.A．explaintherationalebehindabehaviorpatternB．denouncetheactionsofthosewhodonotvoteC．showthesubtleironyofthefriend’sargumentD．offerasolutiontoapressingproblem41Laboratoryresearchisattheheartofscientificlife;scientists’realworkconsistsoftestingoutideasthatcometothemastheyponderthemysteriesoftheworldaroundthem.Anaturalbiologistwalksthroughacityparkoracrossasuburbanlawnandishalf-consciouslywondering:Whytwoleavesinsteadofthree?Whypinkflowersinsteadofwhite?Suchruminationgoesonwithoutendinascientist’smind,acontinuousaccompanimenttotherhythmofdailylife.Whateverascientistisdoing—reading,cooking,talking,playing—sciencethoughtsarealwaysthereattheedgeofthemind.Theyarethewaytheworldistakenin;allthatisseenisfilteredthroughaneverpresentscientificmusing.2Howawould-bescientistdecidesonadiscipline,settlesonaproblem,andgoestoworkisoftenasmuchamailerofchanceasitisoftemperament.Onecaneasilybecomeachemistoraneuroanatomistbecauseofwhereonewenttoschoolorwhoseinfluenceonehappenedtocomeunderasbecauseofacompellingearlyresponsetothelogicofchemistryorthebeautyofthehumannervoussystem.Nomatter.Oncethedisciplineisestablished,theproblemchosen,andthescientistimmersedinthework,heorshebecomesaspersuadedasneedbeofthecentralityandurgencyoftheparticularworkbeingdone.Suchadaptivemyopiaisnecessaryinsciencebecausethegrinding,repetitiveminutenessofdailylaboratoryworkissotime-consuming(forweeks,months,evenyearsatatime)that,often,eventoremembertheoriginalimpetusfortheworkisapsychologicaltrickofthehighestorder.Tostimulatethememorybackintoexistencewithfairregularity,onemustbelieveinthefundamentalimportanceofwhatoneisdoing.Thosewhodoarethemostenergetic,vital,exciting,andexcitedofscientists.3CarolSteiner,ageneticist,comesupwithafinemetaphorforhowtomakeaworkingpropositionofscientificmystery.“Imagine,”shesays,“thatyouhaveajigsawpuzzlewithnopictureprintedonit.Allyouhavearepiecesyouhaven’tacluehowtomakesenseof.Thepiecesareyourseparatescientificobservations.Here’sanexampleofhowyoumighttrytogetahandleonthepuzzle:4“Wehaveamicroorganismwithasecretorystructureononeend.Weknowthisstructureisalwaysonthesameplaceinthecellandthatthepositionofthisstructureisinherited.Thequestionwewanttoansweris,howcaninheritedinformationbetranslatedintopositionalinformation?Whyinthatoneplaceandnoplaceelse?Isthegeneticcodeinvolved,andifso,how?Theanswerwilltellushowthegenesworkinconcertwiththerestofthecelltoputthingswheretheybelong.5“Inordertogatherpiecesofthejigsawpuzzle(thatis,piecesofinformation),wepokeatthecell.Wechangeitalittle….Aspecificmutationthatalteredthemembranestructureofthecellwasfoundtoturnoffthesynthesisofthesecretorystructure.Thiswasapieceofthejigsawpuzzle.Butjustonepiece.Becausewehadn’taclueastohowthishadhappenedorcouldhappen.”Steinerindicatesthattherewillbemanyfurtherquestionsthatwillsuggestexperimentswhoseresultsmayallowustoprintpicturesonthepiecesofthejigsawpuzzle:“Notputthepuzzletogether,mindyou.Buthelpusthinkaboutwhatthepicturewillultimatelylooklike.”6TherealizedpictureonCarolSteiner’sjigsawpuzzleisthemapofgeneexpressionlaidoutclearlywithallroads,pathways,connectingsignalpoints,andrailwayjunctionsmarkedsothatanytouristcanfindhisorherwayinthisbeautifulcountry,whichisconfusingonlywhenoneiswanderingaboutinignorance—asweallarenow—withahighlyincompletemap.49.Theprimarypurposeofthepassageistoconveyinformationaboutthe________.A.occupationalhazardsencounteredbylaboratoryworkers.B.problem-solvingskillstaughtbychemistsandneuroanatomistsC.professionalcollaborationnecessaryforgeneticistsD.thoughtprocessesdistinctivetoresearchscientists50.InLine1,theauthorcharacterizes“laboratoryresearch”assomethingthatis________.A.fundamentalB.ambitiousC.challengingD.time-consuming51.Theauthorindicatesthattheprocessof“rumination”(paragraph1)is________.A.subjectiveB.vexatiousC.incessantD.innovative52.Inparagraph2,“Nomatter”dismissesasirrelevantthemeansbywhich________.A.sciencestudentslearnresearchskillsB.scientistschooseresearchspecialtiesC.laboratoryreportsexplainmethodologiesD.scientificknowledgeisperceivedbythepublic53.The“memory”referredtoinparagraph2isthatofthe________.A.initialfascinationwithascientificgoalB.stepsrequiredtoestablishscientifictruthC.day-to-dayrepetitivenessoftheworkD.relevanttrainingintheacademicfield54.Thepassageimpliesthatthediscoveryofthe“specificmutation”(paragraph5)wasmostsignificantfor________.A.demonstratingtherandomnatureofscientificbreakthroughsB.provingthatmultiplefactorsaffectmicroorganismsC.providingacluetothesolutionofaresearchquestionD.justifyingtheexpenseofamajorresearchproject55.WhichbestdescribesthefunctionofSteiner’saccountofherresearchintheoveralldevelopmentofthepassage?A.Adigressionfromtheauthor’scentralargumentB.ArefutationofcriticismsraisedearlierinthepassageC.AnobservationthatchallengespreviousassertionsD.Anexamplethatexpandsuponprecedinggeneralization51Thedownslopemovementofrock,mud,orothermaterialundertheinfluenceofgravityisknownasmasswasting.Whiletheangleoftheslopeisamajorfactorinthepotentialformasswasting,theslopeisnotthesoledeterminerofmasswastingevents.Waterplaysasignificantrole,especiallywhereitisplentifulduringtherainyseason.Earthquakesmaycauserockslides,mudflows,andothermassmovements.Factorssuchasthepresenceorabsenceofvegetationandhumanactivitiescanalsoinfluencethepotentialformasswasting.2Onewaytoclassifymasswastingprocessesisonthebasisofthematerialinvolved,suchasrock,debris,earth,ormud.Themannerinwhichthematerialmovesisalsoimportantandisgenerallydescribedasafall,aslide,oraflow.Afalloccurswhenweatheringloosensbouldersfromcliffsorrockfaces,causingtheboulderstobreakawayandfall.Aslidetakesplacewhenevermaterialremainsfairlycoherentandmovesalongawell-definedsurface.Aflowinvolvesthemovementofdebriscontainingalargeamountofwater.3Manymasswastingprocessesaredescribedasslides.Rockslidesoccurwhenacoherentmassofrockbreakslooseandslidesdownaslopeasaunit.Ifthematerialinvolvedismostlyseparatepieces,itiscalledadebrisslide.Slidesareamongthefastestandmostdestructivemassmovements.Usuallyrockslidesoccurinageologicsettingwheretherocklayersareinclined,orwheretherearejointsandfracturesintherockthatareparalleltotheslope.Whensucharockunitisundercutatthebaseoftheslope,itlosessupportandtherockeventuallycollapses.Rainorsnowmeltcantriggerarockslidebywettingtheunderlyingsurfacetothepointthatfrictioncannolongerholdtherockinplace.Thefastesttypeofslideisarockavalanche,inwhichamassofrockliterallyfloatsonairasitmovesdownslope.Thehighspeedofarockavalancheistheresultofairbecomingtrappedandcompressedbeneaththefallingmassofdebris,allowingittomovedown