GMAT（VERBAL）逻辑推理模拟试卷21

GMAT(VERBAL)逻辑推理模拟试卷

21

一、逻辑推理(本题共31题，每题7.0分，共31分。)

1、PhishCorunsanumberoffarmsinthearidprovinceofNufa,dependinglargelyon

irrigation.Now,aspartofaplantoefficientlyincreasethefarms*totalproduction,it

planstodrilldowntoanaquifercontainingwarm,slightlysaltywaterthatwillbeusedto

raisefishinponds.Thewaterfromthepondswilllaterbeusedtosupplementpiped-in

irrigationwaterforPhishCo'svegetablefields,andthepondsandaccompanying

vegetationshouldhelpreducetheheatintheareaofthefarms.Whichofthefollowing

would,iftrue,moststronglysuggestthattheplan,ifimplemented,wouldincreasethe

overallefficiencyofPhishCo'sfarms?

A^MostofthevegetationtobeplacedaroundthepondsisnativetoNufa.

B,FishraisedonPhishCo'sfannsarelikelytobesaleableinthenearesturbanareas.

C、Organicwastefromfishinthepondwaterwillhelptofertilizefieldswhereitisused

forirrigation.

D、ThegovernmentofNufawillhelptoarrangeloanrlnancingtopartiallycoverthe

costsofdrilling.

E、Pondswillbelocatedonlow-lyinglandnowpartiallyoccupiedbygraincrops.

标准答案：C

知识点解析：SituationAcompanyplanstoincreasethetotalefficiencyofitsfarmsin

anaridregionbydrillingdowntoanaquiferwhosewaterwillbeusedtoraisefishin

pondsandtohelpirrigatethefamis'vegetablefields.Thepondsandaccompanying

vegetationshouldhelpreducetheheataroundthefarms.ReasoningWhatwouldmakeit

mostlikelythatimplementingtheplanwouldincreasethefarms*overallefficiency?The

farmswillbecomemoreefficientiftheplansignificantlyincreasestheirproductionfor

littleornoaddedcost.AVegetationnativetoanaridregionmaybenomorelikelyto

thrivearoundpondsthannon-nativcvegetationwouldbe,andinanycasewouldnot

clearlyincreasethefarms'totalcropproductionorefficiency.BThismakesitslightly

morelikelythattheplanwouldincreasethefanns'profitability,nottheirefficiencyor

productivity.CCorrect.Fertilizingthefieldswiththewastewhileimgatingthecrops

mightsignificantlyimprovecropproduction.Butitwouldcostlittleornothingextra,

sincethewastewouldalreadybeintheirrigationwater.Thus,thisfeatureoftheplan

wouldlikelyenhancethefarms'efficiencybyincreasingtheirproductivityfbrno

significantextracost.DThisgovernmentassistancemightslightlyreducetheworkthe

companyhastodotoprocurealoan.Butprobablyitwouldneitherincreasethefarms,

productionnorreducetheoverallexpenseofimplementingtheplan(includingthe

expenseincurredbythegovernment).EIfanything,thissuggeststhattheplanmight

reducethefarms'efficiencybyeliminatingproductivecropland.Thecorrectansweris

C.

2、StockholdershavebeencriticaloftheFlynaCompany,amajorfurnitureretailer,

becausemostofFlyna^furnitureismanufacturedinCountryXfromlocalwood,and

illegalloggingiswidespreadthere.However,Flynahassetupacertificationschemefor

lumbermills.Ithashiredastaffofauditorsandforestryprofessionalswhoreview

documentationofthewoodsupplyofCountryX'slumbermillstoensureitslegalorigin,

makesurprisevisitstomillstoverifydocuments,andcertifymillsasapprovedsourcesof

legallyobtainedlumber.Flynausesonlylumberfromcertifiedmills.Thus,Flyna'sclaim

thatitsCountryXwoodsupplyisobtainedlegallyisjustified.Whicholthefollowing,if

true,wouldmostunderminethejustificationprovidedforFlyna'sclaim?

A^Onlyaboutone-thirdofFlyna'sinspectorswerehiredfromoutsidethecompany.

B、CountryX'sgovernmentrecentlyreduceditssubsidiesfbrlumberproduction.

C^Flynahashadtopayhigherthanexpectedsalariestoattractqualifiedinspectors

D、TheproportionofCountryX'slumbermillsinspectedeachyearbyFlyna'sstaffis

about10percent,randomlyselected.

E、IllegalloggingcostsCountryX'sgovernmentasignificantamountinlostrevenue

eachyear.

标准答案：D

知识点解析：SituationTheFlynaCompanysellsfurnituremostlymadeinCountryX

fromlocalwood.IllegalloggingiswidespreadinCountryX.Flynahassetupa

certificationschemeforlumbermills.SpecializedstaffmakesurprisevisitstoCountryX

mills,inspectdocumentationtoensurethatthewoodsupplyhasalegalorigin,andcertify

millsasapprovedsourcesfbrlegallyobtainedlumber.Flynausesonlylumberfrom

certifiedmills.Accordingtotheargument,Flyna'sclaimthatitswoodsupplyislegally

obtainedisjustified.ReasoningWhatadditionalinformationwould,iftrue,most

underminethejustificationfbrFlyna'sclaimthatitsCountryXwoodislegallyobtained?

Clearly,muchdependsonthethoroughnessofthecerlificationscheme.Forexample,the

staffauditingthemillswouldneedtobequalifiedforthejobandmeticulousinmeeting

theirresponsibilities.Theauditingvisitswouldneedtobefrequentenough,andnot

predictablebymillmanagement.Flynawouldneedtobegenuinelycommittedto

ensuringlegalityofwoodsources;itwouldneedtomonitoritsstafftoensurethatthey

weredoingtheirjobseffectively.AThissuggeststhatFlynacouldmakegoodjudgments

astothecompetenceandtrustworthinessofmostoftheinspectorshiredtocertifylumber

mills.BThiscouldprovideaperverseincentivetologgerstoviolatelegalrestrictionson

logging.However,thiswouldnotundercutFlyna'sjustificationfbritsclaimthatits

systemensuresthatallitslumberislegallysourced.CThishasnobearingonwhether

Flyna'scertificationsystemwillbeeffectiveinguaranteeingthatFlyna'slumberis

legallysourced.Wearenottold,forexample,thatFlynahasbeenunabletofindenough

qualifiedinspectorsforthecertificationsystemtobeeffective.DCorrect.Thismeans

that90percentofCountr/X'scertifiedlumbermillsarcnotinspectedinanyparticular

year.Moreover,sincetheselectionofthe10percentoflumbermillstobeinspectedina

givenyearisrandom,somelumbermillsmightgofbrmuchlongerthantenyearswithout

inspection;duringthisperiod,manyofthosemillsmightfallbelowcertification

standardsandevenuselumberillegallyobtained.EThisindicatesthatasignificant

amountofillegalloggingoccursinCountryX;thissuggeststhatitispossiblethatsome

illegallysourcedwoodcouldfinditswaytolumbermillsthatFlynausesandhas

certified.Buttheinformationgivenhereisnotsufficientlyspecifictoindicatethatthe

Flynacertificationsystemwouldfailtopreventthecompany'suseofillegallysourced

wood.ThecorrectanswerisD.

3、TheXCTautomobileisconsideredlessvaluablethantheZNKautomobile,because

insurancecompaniespayless,onaverage,toreplaceastolenXCTthanastolenZNK.

Surprisingly,theaverageamountinsurancecompanieswillpaytorepairacarinvolvedin

acollisionistypicallyhigherfortheXCTthanfortheZNK.Oneinsuranceexpert

explainedthatrepairstoXCTautomobilesareespeciallylabor-intensive,andlaborisa

significantfactorincollisionrepaircosts.Whichofthefollowing,iftrue,moststrongly

supportstheinsuranceexpert'sexplanation?

A、ZNKautomobilesareinvolvedinaccidentsmorefrequentlythanXCTautomobiles.

B、ThecostofroutinemaintenancefortheZNKisaboutthesameasfortheXCT.

C、TherearemoreautomobilemechanicswhospecializeinXCTrepairsthaninZNK

repairs.

D、TheeaseofrepairofZNKautomobilesisonefactorthataddstotheirvalue.

E^XCTautomobilesaremorelikelytobestolenthanZNKautomobiles.

标准答案：D

知识点解析：SituationTwoautomobilemodelsXCTandZNKarecomparedwith

respectto(1)whatinsurancecompaniespayonaveragetoreplaceastolenvehicleand

(2)whatinsurancecompaniespayonaveragetorepairacrashedvehicle.On(I),

insurancecompaniespaylessforXCTsthanforZNKs.On(2),insurancecompaniespay

moreforrepairingXCTsthanZNKs.AninsuranceexpertexplainsthatrepairstoXCTs

areespeciallylabor-intensive;thistendstoraisethecostofrepairs.ReasoningWhich

pieceofnewinformationmoststronglysupportstheexpertsexplanationfbrthefactthat

thereplacementvalueisgreaterforthecarthathaslowerrepaircosts?Weshouldlook

forinformationthatsupplementstheexplanationinawaythatshowsthecoherenceofthe

twofactsgivenregardinginsurancepaymentsfbrthetwocars.AThefrequencyof

accidentsisnotdirectlyrelevanttothehighercostofcollisionrepairfbrthoseXCTsthat

areinvolvedincollisions.BThisinformationisnotdirectlyrelevanttothehighercostof

collisionrepairforXCTs.ItneitherunderminesnorsupportstheclaimthatXCTlabor

costsarehigherpercrashedvehicleanddoesnothelpsupportthatclaimasan

explanationforthediscrepancyinquestion.CThisneithersupportsnorunderminesthe

expert'sexplanation.IfwehadinformationconcerningthesupplyofXCTmechanicsand

ZNKmechanicsrelativelothedemandforeach,wewouldhavesomeevidencethat

couldthrowlightondifferencesinlaborcosts.DCorrect.ZNKsaremorevaluable

becausebuyersknowthattotalrepaircostswillbelower.Thisisreflectedinthemarket

valueofZNKscomparedtothatofXCTs.ReplacingastolenXCTcostsinsurance

companieslessthanreplacingastolenZNKbecausethelowermarketvalueofXCTsis

relatedinthehighcostofcollisionrepair.EThisisunlikelytolowerthemarketvalueof

XCTs.ThemarketvalueofXCTsisthefactorthatdetermineshowmuchitcoststo

replaceastolenXCT.ThecorrectanswerisD.

4、Thesustainedmassiveuseofpesticidesinfarminghastwoeffectsthatareespecially

pernicious.First,itoftenkillsoffthepests'naturalenemiesinthearea.Second,itoften

unintentionallygivesrisetoinsecticide-resistantpests,sincethoseinsectsthatsurvivea

particularinsecticidewillbetheonesmostresistanttoit,andtheyaretheonesleftto

breed.Fromthepassageabove,itcanbeproperlyinferredthattheeffectivenessofthe

sustainedmassiveuseofpesticidescanbeextendedbydoingwhichofthefollowing,

assumingthateachisarealisticpossibility?

A、Usingonlychemicallystableinsecticides

B、Periodicallyswitchingthetypeofinsecticideused

C、Graduallyincreasingthequantitiesofpesticidesused

D^Leavingafewfieldsfalloweveryyear

E、Breedinghigher-yieldingvarietiesofcropplants

标准答案：B

知识点解析：SituationContinuedhigh-levelpesticideuseoftenkillsoffthetargeted

pests5naturalenemies.Inaddition,thepeststhatsurvivetheapplicationofthepesticide

maybecomeresistanttoit,andthesepesticide-resistantpestswillcontinuebreeding.

ReasoningWhatcanbedonetoprolongtheeffectivenessofpesticideuse?Itcanbe

inferredthattheongoinguseofaparticularpesticidewillnotcontinuetobeeffective

againstthefuturegenerationsofpestswithaninherentresistancetothatpesticide.What

wouldbeeffectiveagainstthesefuturegenerations?Iffannersperiodicallychangethe

particularpesticidetheyuse,thenpestsresistanttoonekindofpesticidemightbekilled

byanother.Thiswouldcontinue,withpestsbeingkilledoffincyclesasthepesticidesare

changed.Itisalsopossiblethatthisrotationmightallowsomeofthepests*natural

enemiestosurvive,atleastuntilthenextcycle.ANotenoughinformationabout

chemicallystableinsecticidesisgiventomakeasoundinference.BCorrect.This

statementproperlyidentifiesanactionthatcouldextendtheeffectivenessofpesticide

use.CGraduallyincreasingtheamountofthepesticidesbeingusedwillnothelpthe

situationsincethepestsarealreadyresistanttoit.DContinueduseofpesticidesis

assumedaspartoftheargument.Sincepesticideswouldbeunnecessarylorfallowfields,

thissuggestionkirrelevant.EBreedinghigher-yieldingvarietiesofcropsdoesnothingto

extendtheeffectivenessoftheuseofpesticides.ThecorrectanswerisB.

5、Whichofthefollowing,iftrue,mostlogicallycompletestheargumentbelow?

Manufacturersarenowrequiredtomakeallcigarettelighterschild-resistantbyequipping

themwithsafetylevers.Butthischangeisunlikelytoresultinasignificantreductionin

thenumberoffirescausedbychildrenplayingwithlighters,becausechildrengiventhe

opportunitycanfigureouthowtoworkthesafetyleversand.

A、theadditionofthesafetylevershasmadelightersmoreexpensivethantheywere

beforetherequirementwasinstituted

B、adultsaremorelikelytoleavechild-resistantlightersthannon-child-resistantlighters

inplacesthatareaccessibletochildren

C>manyofthefiresstartedbyyoungchildrenarcquicklydetectedandextinguishedby

theirparents

D、unlikechild-resistantlighters,lightersthatarenotchild-resistantcanbeoperatedby

childrenasyoungastwoyearsold

E、approximately5,000firesperyearhavebeenattributedtochildrenplayingwith

lightersbeforethesafetyleverswererequired

标准答案：B

矢口识点解析：SituationManufacturersmustequipallcigarettelighterswithchild-

rcsistantsafetylevers,butchildrencanfigureouthowtocircumventthesafetyleversand

therebyoftenstartfires.ReasoningWhatpointwouldmostlogicallycompletethe

argument?Whatwouldmakeitlikelythatthenumberoffirescausedbychildrenplaying

withlighterswouldremainthesame?Inorderforchildrentcstartfiresusinglighters

equippedwithsafetylevers,theymustbegiventheopportunitytofigureouthowthe

safetyleversworkandthentousethem.Theymust,thatis,haveaccesstothelighters.A

Ifsafety-lever-equippedlightersaremoreexpensivethanlightersthatarenotso

equipped,fewerlightersmightbesold.Thiswouldmostlikelyaffordchildrenlessaccess

tolighters,thusgivingthemlessopportunitytostartfireswiththem.BCorrect.This

statementproperlyidentifiesapointthatlogicallycompletestheargument:itexplains

whychildrenarelikelytohaveaccesstolightersequippedwithsafetylevers.CThe

speedwithwhichfiresareextinguisheddoesnothaveanybearingonthenumberoffires

thatarestarted.DThisprovidesareasontobelievethatthenumberoffiresstartedby

childrenwillmostlikelydecrease,ratherthanstaythesame:fewerchildrenwillbeable

tooperatethelighters,andthusfewerfiresarelikelytobestarted.EThisinformation

abouthowmanyfireswerestartedbychildrenbeforesafetyleverswererequireddoes

nothaveanybearingonthequestionofhowmanyfiresarelikelytobestartedby

childrennowthatthesafetyleversarerequired.ThecorrectanswerisB.

6、Whichofthefollowingmostlogicallycompletesthepassage?Abusinessanalysisof

theAppenianrailroadsystemdivideditslong-distancepassengerroutesintotwo

categories:ruralroutesandinterurbanroutes.Theanalysisfoundthat,unlikethe

interurbanroutes,fewruralroutescarriedahighenoughpassengervolumetobe

profitable.Closingunprofitableruralroutes,however,willnotnecessarilyenhancethe

profitabilityofthewholesystem,since.

A^alargepartofthepassengervolumeoninterurbanroutesisaccountedforby

passengerswhobeginorendtheirjourneysonruralroutes

withinthelasttwodecadesseveraloftheleastusedruralrouteshavebeenclosedand

theirpassengerserviceshavebeenreplacedbybuses

C^theruralrouteswerealloriginallyconstructedatleastonehundredyearsago,

whereassomeoftheinterurbanrouteswereconstructedrecentlyfornewhigh-speed

expresstrains

D、notallofAppenia'slargecitiesareequallywellservedbyinterurbanrailroad

services

E、thegreatestpassengervolume,relativetotheroutes'capacity,isnotoneither

categoryoflong-distanceroutesbutisonsuburbancommuterroutes

标准答案：A

知识点解析：SituationIntheAppenianrailroadsystem,interurbanroutesgenerally

carryenoughpassengerstobeprofitable,butfewruralroutesdo.ReasoningWhatwould

suggestthatclosingunprofitableruralrouteswouldnotenhancetherailroadsystems

profitability?Anyevidencethatclosingtheunprofitableruralrouteswouldindirectly

reducetheprofitabilityofothercomponentsoftherailroadsystemwouldsupportthe

conclusionthatclosingthoseruralrouteswillnotenhancethesystem'sprofitability.

Thus,astatementprovidingsuchevidencewouldlogicallycompletethepassage.A

Correct.Thissuggeststhatclosingtheruralroutescoulddiscouragemanypassengers

fromtravelingontheproRtableinterurbanroutesaswell,thusreducingtheprofitability

oftherailroadsystemasawhole.BEvenifsomeoftheleastusedruralrouteshave

alreadybeenclosed,itremainstruethatmostoftheremainingruralroutesaretoolittle

usedtobeprofitable.CClosingveryoldrouteswouldbeatleastaslikelytoenhancethe

railroadsystem'sprofitabilityasclosingnewerrouteswouldbe.DEvenifthereisbetter

railroadservicetosomelargecitiesthanothers,closingunprofitableruralroutescould

stillenhancethesystem'sprofitability.EEvenifsuburbanroutesarethemostheavily

usedandprofitable,closingunderused,unprofitableruralroutescouldstillenhancethe

system'sprofitability.ThecorrectanswerisA.

7、Initssearchfornewtechnologiesforsolarenergythatcanproducelower-cost

electricity,Smith-Diatomisdevelopinganewwaytomakedye-sensitivesolar-cells,in

whichphotonsstrikelight-sensitivedyes.Theprocessusesdiatoms,whichareunicellular

algaethathavesiliconshellswithacomplexstructure.First,theorganicmaterialis

removed,andthentheshellsarecoatedwithatitaniumdioxidefilmthatactsasa

semiconductor.Thediatoms5stmetureresultsinmorephotonactivityandthusmore

efficientproductionofelectricitythanwithcurrentdye-sensitizedsolarcells,whichin

turnlowersthecost.Whichofthefollowingconsiderationswould,iftrue,moststrongly

supportthehypothesisthattheplan,ifimplemented,willproducelow-costelectricity

fromdye-sensitivesolarcells?

Diatomsareanimportantlinkinoceanicfoodchainsandhelpcyclecarbondioxide

fromtheatmosphere.

B、Thecurrentcostofelectricityproducedbydye-sensitivesolarcellsisroughlythree

timesthatofnon-solarelectricity.

C^Becausediatomsoccurnaturally,nospecialengineeringprocessesareneededto

producethebasicdye-sensitivesolarcellstructures.

D^Dye-sensitivesolarcellsworksomewhatmoreefficientlyinlowerlightthan

previoussolarcelltechnologies.

E、Theproductionofdye-sensitivesolarcellsprimarilyusesmaterialsthatdonotharm

theenvironment.

标准答案：C

知识点解析：SituationSmith-Diatomistryingtodevelopanewwaytomakedye­

sensitivesolarcellsinhopesofdevelopingameansforusingsolarenergytoproduce

lower-costelectricity.Theirnewtechnologywillusediatoms,single-celledalgaewith

siliconshellsthathaveacomplexstructure.Thisstructureresultsinincreasedphoton

activity,whichresultsinmoreefficientandlower-costenergyproductionthancurrent

dye-sensitivesolarcellsdo.ReasoningWhatstatementwouldprovidethestrongest

supportfbrtheclaimthatSmith-Diatomsplanwouldresultintheproductionoflower-

costenergythancanbeattainedfromthecurrentdye-sensitivesolarcells?Onepotential

problemwithSmith-Diatom^planwouldbeiftheintendeduseofdiatomswouldbe

costly.Anystatementthatruledoutapotentiallycostlyaspectsofproduction,e.g.,costly

engineeringprocesses,wouldprovidesupportfbrtheclaiminquestion.ANothingin

Smith-Diatonfsplanisrelatedtodiatom'sconnectiontooceanicfoodchainsortotheir

roleincyclingcarbondioxidefromtheatmosphere.BThatproducingelectricityby

meansofdye-sensitivesolarcellsismuchmorecostlythanothertypesofelectricity

productionwouldhelpexplainwhySmith-Diatomwantstofindalower-costmeansof

producingsolarenergy,butitdoesnotgiveusreasontothinkthatSmith-Diatom^plan

willbesuccessful.CCorrect.Ifnospecialengineeringprocessesareneededtocarryout

Smith-Diatom'splan,onepotentialcostlyaspectofsolar-electricityproductionisruled

out,therebyprovidingsomereasontothinkSmith-Diatom'sgoalofproducinglower-cost

electricitymightbeattainable.DThefactthatdye-sensitivesolarcellsworkmore

efficientlyinlowerlightthanothersolarcelltechnologieswouldhelpsupporttheclaim

inquestiononlyifweknewthatthecostofproducingsuchcellsisnotprohibitive.Also,

itcouldbethecasethatalthoughdye-sensitivesolarcellsworkmoreefficientlyinlower

lightthanothersolarcelltechnologies,theothersolarcelltechnologiesmightworkmuch

moreefficientlyingoodlightingconditions.EIftheproductionofdye-sensitivesolar

cellsdoesnotharmtheenvironment,thatmightbegoodreasontousesuchsolarcells,

butitisnotrelevanttodeterminingwhetherSmith-Diatom'splanwillbelikelytoattain

itsgoal.ThecorrectanswerisC.

8、AlthoughAckerburg'ssubwaysystemiscurrentlyoperatingatadeficit,thetransit

authoritywilllowersubwayfaresnextyear.Theauthorityprojectsthatthelowerfares

willresultinatenpercentincreaseinthenumberofsubwayriders.Sincetheadditional

incomefromthelargerridershipwillmorethanoffsetthedecreaseduetolowerfares,the

transitauthorityactuallyexpectsthefarereductiontoreduceoreliminatethesubway

system'soperatingdeficitfbrnextyear.Whichofthefollowing,iftrue,providesthe

mostsupportfbrthetransitauthority'sexpectationofreducingthesubwaysystem's

operatingdeficit?

A^Throughouttheyearsthatthesubwaysystemhaseperated,fareshaveneverbefore

beenreduced.

Theplannedfarereductionwillnotapplytostudents,whocanalreadyridethe

subwayfbrareducedfare.

C、Nextyear,thetransitauthoritywillhavetoundertakeseverallarge-scaletrack

maintenanceprojects.

D、Thesubwaysystemcanaccommodateatenpercentincreaseinridershipwithout

increasingthenumberoftrainsitrunseachday.

E、ThecurrentsubwayfaresinAckerburgarehigherthansubwayfaresinothercitiesin

theregion.

标准答案：D

知识点解析：SituationAckerburg'stransitauthorityplanstolowersubwayfares,

projectingthatthiswillincreaseridershipby10percentandtherebyreduceoreliminate

thesubwaysystem'soperatingdeficit.ReasoningWhaievidencewouldsupportthe

expectationthatloweringsubwayfareswillreducetheoperatingdeficit?Thepassage

saystheadditionalincomefromtheprojectedincreaseinridershipwillmorethanoffset

thedecreaseduetotheloweredfares.Theclaimthatloweringfareswillreducethe

operatingdeficitcouldbesupportedeitherbyadditionalevidencethatloweringthefares

willincreaseridershipatleastasmuchasprojectedorbyevidencethattheplanwillnot

increaseoveralloperatingexpenses.AThefactthatfareshaveneverbeenreduced

providesnoevidenceaboutwhatwouldhappeniftheywerereduced.BThissuggests

thattheplannedfarereductionwouldnotaffectrevenuefromstudentriders,butitdocs

notsuggesthowitwouldaffectrevenuefromallotherriders.CThesemaintenance

projectswillprobablyincreasetheoperatingdeficit,makingitlesslikelythatthefare

reductionwillreduceoreliminatethatdeficit.DCorrect.Thisindicatesthattheplanwill

notinvolveextraoperatingexpensesforrunningtrainsandthusincreasesthelikelihood

thattheplanwillreducetheoperatingdeficit.EAckerburgmaydifferfromothercitiesin

theregioninwaysthatmakethehigherfhresoptimalforAckerburg'ssubwaysystem.

ThecorrectanswerisD.

9、AtseverallocationsonthenorthwestcoastofNorthAmericaareformationsknown

aschevrons-wedge-shapedformationsofmoundedsediment-pointingtowardthe

ocean.Mostgeologiststakethemtohavebeenformedbyerosion,butrecentlyother

scientistshaveproposedthattheywerethrownupfromtheoceanbymassivewaves

triggeredbymeteorimpactsinthePacificOcean.Whichofthefollowing,ifdiscovered,

wouldmosthelpindecidingwhichhypothesisiscorrect?

A^Chevron-likestructureswhicharenotcurrentlynearglaciers,largerivers,orother

bodiesofwater

B、Thepresence,inchevrons,ofdepositsofoceanmicrofossilscontainingmetals

typicallyformedbymeteorimpacts

C、Oral-historyevidenceforfloodingthatcouldhavebeencausedbyoceanwaves

D、Thefactthatexactdataaboutthelocationanddepthofanymeteorimpactcraterson

thePacificseabedislacking

E、Thefactthatcertainchangesintheshapeandlocationofmaritimesandduneshave

beenproducedbytheactionofwindandwaves

标准答案：B

知识点解析：SituationThenorthwestcoastofNorthAmericahaschevrons—large

wedge-shapedmoundsofsedimen—pointingtowardtheocean.Twoexplanationshave

beenofferedforthesephenomena:(1)theywereformedbyerosion,accordingtomost

geologists;and(2)meteorimpactscausedmassivewavesthatthrewtheformationsup

fromthePacificOcean.ReasoningWhichoftheanswerchoicesmosthelpstodecide

whichexplanationiscorrect?If(2)isthetrueexplanation,thenonewouldexpect

evidencesuchasresiduesofoceanmattertobepresentinchevrons.If(1)isthetrue

explanation,thechevronswouldneedtobeanalyzedtodeterminethesourcesofthe

erodedmaterial,andthefactors,suchaswindorwater,thatproducedtheerosion.AThis

informationneitherconfirmsnorconclusivelyeliminateseitherexplanation(1)or

explanation(2).Thescientistshypothesizeisthatthesechevrons,attheselocationson

thecoast,werecausedbymeteorimpacts,notthatgeologicalstructureswithasimilar

shapearegenerallyformedinthatway.Thescientistits'reasoningisconsistentwiththe

hypothesisthatdifferentwedge-shapedgeologicalstructuresareformedinmany

differentways.BCorrect.Theoceanmicrofossilscontainingmetalstypicallyfoundin

meteorswouldindicatethatthemetalswerefoundinfossilsthatoriginatedintheocean.

Thisprovidesstrongevidencethatmeteorslandedintheocean;thefactthatthemetals

arenowfoundinthechevronsstronglysupportsexplanation(2).CTheoral-history

testimonyconcerningfloodingbyoceanwavesprovidesweakevidenceconsistentwith

eachofthetwoexplanations.Erosionofrockscandepositsediment,andoceanwaves

couldformmoundsofsuchsediment.DThisinformationpointsoutthatsomeadditional

bitsofevidencethatmighthelpconfirmexplanation[2)arccurrentlylacking,but