TPO25阅读文本.docx
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TPO25阅读文本
TPO25
ThesurfaceofMars
P1ThesurfaceofMarsshowsawiderangeofgeologicfeatures,includinghugevolcanoes-thelargestknowninthesolarsystem-andextensiveimpactcratering.ThreeverylargevolcanoesarefoundontheTharsisbulge,anenormousgeologicareanearMars’sequator.NorthwestofTharsisisthelargestvolcanoofall:
OlympusMons,withaheightof25kilometersandmeasuringsome700kilometersindiameteratitsbase.ThethreelargevolcanoesontheTharsisbulgearealittlesmaller-a“mere”18kilometershigh.
P2NoneofthesevolcanoeswasformedasaresultofcollisionsbetweenplatesoftheMartiancrust-thereisnoplatemotiononMars.Instead,theyareshieldvolcanoes-volcanoeswithbroad,slopingslidesformedbymoltenrock.AllfourshowdistinctivelavachannelsandotherflowfeaturessimilartothosefoundonshieldvolcanoesonEarth.ImagesoftheMartiansurfacereveal
manyhundredsofvolcanoes.MostofthelargestvolcanoesareassociatedwiththeTharsisbulge,butmanysmalleronesarefoundinthenorthernplains.
P3ThegreatheightofMartianvolcanoesisadirectconsequenceoftheplanet’slowsurfacegravity.Aslavaflowsandspreadstoformashieldvolcano,thevolcano’seventualheightdependsonthenewmountain’sabilitytosupportitsownweight.Thelowerthegravity,thelessertheweightandthegreatertheheightofthemountain.ItisnoaccidentthatMaxwellMonsonVenusandtheHawaiianshieldvolcanoesonEarthrisetoaboutthesameheight(about10kilometers)abovetheirrespectivebases-EarthandVenushavesimilarsurfacegravity.Mars’ssurfacegravityisonly40percentthatofEarth,sovolcanoesriseroughly2.5timesashigh.AretheMartianshieldvolcanoesstillactive?
Scientistshavenodirectevidenceforrecentorongoingeruptions,butifthesevolcanoeswereactiveasrecentlyas100millionyearsago(anestimateofthetimeoflasteruptionbasedontheextentofimpactcrateringontheirslopes),someofthemmaystillbeatleastintermittentlyactiveMillionsofyears,though,maypassbetweeneruptions.
P4AnotherprominentfeatureofMars’ssurfaceiscratering.TheMarinerspacecraftfoundthatthesurfaceofMars,aswellasthatofitstwomoons,ispittedwithimpactcratersformedbymeteoroidsfallinginfromspace.AsonourMoon,thesmallercratersareoftenfilledwithsurfacematter-mostlydust-confirmingthatMarsisadrydesertworld.However,Martiancratersgetfilledinconsiderablyfasterthantheirlunarcounterparts.OntheMoon,ancientcraterslessthan100metersacross(correspondingtodepthsofabout20meters)havebeenobliterated,primarilybymeteoriticerosion.OnMars,therearerelativelyfewcraterslessthan5kilometersindiameter.TheMartianatmosphereisanefficienterosiveagent,withMartianwindstransportingdustfromplacetoplaceanderasingsurfacefeaturesmuchfasterthanmeteoriticimpactsalonecanobliteratethem.
P5AsontheMoon,theextentoflargeimpactcratering(i.e.craterstoobigtohavebeenfilledinbyerosionsincetheywereformed)servesasanageindicatorfortheMartiansurface.AgeestimatesrangingfromfourbillionyearsforMars’ssouthernhighlandstoafewhundredmillionyearsintheyoungestvolcanicareaswereobtainedinthisway.
P6ThedetailedappearanceofMartianimpactcratersprovidesanimportantpieceofinformationaboutconditionsjustbelowtheplanet’ssurface.Martiancratersaresurroundedbyejecta(debrisformedasaresultofanimpact)thatlooksquitedifferentfromitslunarcounterparts.AcomparisonoftheCopernicuscraterontheMoonwiththe(fairlytypical)craterYutyonMarsdemonstratesthedifferences.Theejectasurroundingthelunarcraterisjustwhatonewouldexpectfromanexplosionejectingalargevolumeofdust,soil,andboulders.■However,theejectaonMarsgivesthedistinctimpressionofaliquidthathassplashedorflowedoutofcrater.■Geologiststhinkthatthisfluidizedejectacraterindicatesthatalayerofpermafrost,orwaterice,liesjustafewmetersunderthesurface.■Explosiveimpactsheatedandliquefiedtheice,resultinginthefluidappearanceoftheejecta.■
Q1Theword“enormous”inthepassageisclosestinmeaningto
A.Important
B.Extremelylarge
C.Highlyunusual
D.Active
Q2Accordingtoparagraph1,OlympusMonsdiffersfromvolcanoesontheTharsisbulgeinthatOlympusMons
A.Hasmorecomplexgeologicfeatures
B.Showslessimpactcratering
C.Istaller
D.Wasformedatalatertime
Paragraph1
Q3Theword“distinctive”inthepassageisclosestinmeaningto
A.Deep
B.Complex
C.Characteristic
D.Ancient
Q4Accordingtoparagraphs1and2,whichofthefollowingisNOTtrueoftheshieldvolcanoesontheTharsisbulge?
A.Theyhavebroad,slopingsides.
B.TheyaresmallerthanthelargestvolcanoonMars.
C.TheyhavechannelsthatresemblethelavachannelsofvolcanoesonEarth.
D.Theyareover25kilometerstall.
Paragraph1and2
Q5Theword“roughly”inthepassageisclosestinmeaningto
A.Typically
B.Frequently
C.Actually
D.Approximately
Q6Inparagraph3,whydoestheauthorcompareMaxwellMonsonVenustotheHawaiianshieldvolcanoesonEarth?
A.Tohelpexplaintherelationshipbetweensurfacegravityandvolcanoheight
B.ToexplainwhyMars’ssurfacegravityisonly40percentofEarth’s
C.TopointoutdifferencesbetweenthesurfacegravityofEarthandthesurfacegravityofVenus
D.Toarguethattherearemoresimilaritiesthandifferencesbetweenvolcanoesondifferentplanets
Paragraph3
Q7Whichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepassage?
Incorrect
choiceschangethemeaninginimportantwaysorleaveoutessentialinformation.
A.Althoughdirectevidenceofrecenteruptionsislacking,scientistsbelievethatthesevolcanoeswereactiveasrecentlyas100
millionyearsago.
B.Scientistsestimatethatvolcanoesactivemorerecentlythan100yearsagowillstillhaveextensiveimpactcrateringontheir
slopes.
C.If,assomeevidencesuggests,thesevolcanoeseruptedasrecentlyas100millionyearsago,theymaycontinuetobe
intermittentlyactive.
D.Althoughthesevolcanoeswereactiveasrecentlyas100millionyearsago,thereisnodirectevidenceofrecentorongoing
eruptions.
Q8Theword“considerably”inthepassageisclosestinmeaningto
A.Frequently
B.Significantly
C.Clearly
D.Surprisingly
Q9Accordingtoparagraph4,whatisdemonstratedbythefactthatcratersfillinmuchfasteronMarsthanontheMoon?
A.ErosionfrommeteoriticimpactstakesplacemorequicklyonMarsthanontheMoon.
B.ThereismoredustonMarsthanontheMoon.
C.ThesurfaceofMarsisadrydesert.
D.WindisapowerfulerodingforceonMars.
Paragraph4
Q10Inparagraph4,whydoestheauthorpointoutthatMarshasfewancientcratersthatarelessthan5kilometersindiameter?
A.ToexplainwhyscientistsbelievethatthesurfacematterfillingMartiancratersismostlydust
B.ToexplainwhyscientistsbelievethattheimpactcratersonMarswerecreatedbymeteoroids
C.TosupporttheclaimthattheMartianatmosphereisanefficienterosiveagent
D.ToarguethatMarsexperiencedfewerancientimpactsthantheMoondid
Paragraph4
Q11Accordingtoparagraph5,whathavescientistsbeenabletodeterminefromstudiesoflargeimpactcrateringonMars?
A.SomeMartianvolcanoesaremucholderthanwasoncethought.
B.TheageofMars’ssurfacecanvaryfromareatoarea.
C.Largeimpactcratersarenotreliableindicatorsofageinareaswithhighvolcanicactivity.
D.SomeareasoftheMartiansurfaceappeartobeolderthantheyactuallyare.
Paragraph5
Q12Accordingtoparagraph6,theejectaofMars’scraterYutydiffersfromtheejectaoftheMoon’sCopernicuscraterinthat
theejectaoftheYutycrater
A.Hasnowbecomepartofapermafrostlayer
B.Containsalargevolumeofdust,soilandboulders
C.Suggeststhatliquidoncecameoutofthesurfaceatthecratersite
D.Wasthrownacomparativelylongdistancefromthecenterofthecrater
Paragraph6ismarkedwithanarrow>
Q13Lookatthefoursquares【■】thatindicatewherethefollowingsentencecouldbeaddedtothepassage.
ThissurfacefeaturehasledtospeculationaboutwhatmaylieunderMars’ssurface.
Wherewouldthesentencebestfit?
Clickonasquaretoaddthesentencetothepassage.
Q14Directions:
Anintroductorysentenceforabriefsummaryofthepassageisprovidedbelow.Completethesummaryby
selectingtheTHREEanswerchoicesthatexpressthemostimportantideasinthepassage.Somesentencesdonotbelonginthe
summarybecausetheyexpressideasthatarenotpresentedinthepassageorareminorideasinthepassage.Thisquestionis
worth2points.
Dragyouranswerchoicestothespaceswheretheybelong.Toremoveananswerchoice,clickonit.Toreviewthepassage,
clickVIEWNEXT.VolcanoesandimpactcratersaremajorfeaturesofMartiangeology.
A.PlatemotiononMars,onceconsideredtohaveplayednoroleinshapingtheplanet’ssurface,isnowseenasbeingdirectly
associatedwiththeplanet’searliestvolcanoes.
B.Marshasshieldvolcanoes,someofwhichareextremelytallbecauseoftheplanet’slowsurfacegravity.
C.AlthoughtheerosivepoweroftheMartianatmosphereensuresthatMarshasfewercratersthantheMoondoes,impact
cratersareprominentonMars’ssurface.
D.ScientistscannotyetreliablyestimatetheageoftheMartiansurfacebecausetherehasbeento