托福阅读练习 辅导讲义汇编

Exampleone:

Certainlynocreatureintheseaisodderthanthecommonseacucumber.Allliving

creature,especiallyhumanbeings,havetheirpeculiarities,buteverythingabout

the

littleseacucumberseemsunusual.Whatelsecanbesaidaboutabizarreanimal

that,

Lineamongothereccentricities,eatsmud,feedsalmostcontinuouslydayandnight

butcan

(5)livewithouteatingforlongperiods,andcanbepoisonousbutisconsidered

supremely

ediblebygourmets?

Forsomefiftymillionyears,despiteallitseccentricities,theseacucumberhas

subsistedonitsdietofmud.Itisadaptableenoughtoliveattachedtorocksbyits

tube

feet,underrocksinshallowwater,oronthesurfaceofmudflats.Commonincool

(10)wateronbothAtlanticandPacificshores,ithastheabilitytosuckupmudor

sandand

digestwhatevernutrientsarepresent.

Seacucumberscomeinavarietyofcolors,rangingfromblacktoreddish-brownto

sand-colorandnearlywhite.Oneformevenhasvividpurpletentacles.Usuallythe

creaturesarecucumber-shaped-hencetheirname-andbecausetheyaretypically

(15)rockinhabitants,thisshape,combinedwithflexibility,enablesthemto

squeeze

intocreviceswheretheyaresafefrompredatorsandoceancurrents.

Althoughtheyhavevoraciousappetites,eatingdayandnight,seacucumbershave

thecapacitytobecomequiescentandliveatalowmetabolicrate-feedingsparingly

ornotatallforlongperiods,sothatthemarineorganismsthatprovidetheirfood

have

(20)achancetomultiply.Ifitwerenotforthisfaculty,theywoulddevourallthe

food

availableinashorttimeandwouldprobablystarvethemselvesoutofexistence.

Butthemostspectacularthingabouttheseacucumberisthewayitdefendsitself.

Itsmajorenemiesarefishandcrabs,whenattacked,itsquirtsallitsinternalorgans

intothewater.Italsocastsoffattachedstructuressuchastentacles.Thesea

cucumber

(25)willeviscerateandregenerateitselfifitisattackedoreventouched;itwilldo

thesame

ifthesurroundingwatertemperatureistoohighorifthewaterbecomestoo

polluted.

8.Whatdoesthepassagemainlydiscuss?

(A)Thereasonfortheseacucumber'sname

(B)Whatmakestheseacucumberunusual

(C)Howtoidentifytheseacucumber

(D)Placeswheretheseacucumbercanbefound

9.Inline3,theword"bizarre"isclosestinmeaning

to

(A)odd

(B)marine

(C)simple

(D)rare

10.AccordingtothePassage,whyistheshapeof

seacucumbersimportant?

(A)Ithelpsthemtodigesttheirfood.

(B)Ithelpsthemtoprotectthemselvesfrom

danger.

(C)Itmakesiteasierforthemtomovethrough

themud.

(D)Itmakesthemattractivetofish.

11.Thewords"thisfaculty"inline20refertothe

seacucumber'sabilityto

(A)squeezeintocrevices

(B)devourallavailablefoodinashorttime

(C)suckupmudorsand

(D)liveatalowmetabolicrate

12.Thefourthparagraphofthepassageprimarily

discusses

(A)thereproductionofseacucumbers

(B)thefoodsourcesofseacucumbers

(C)theeatinghabitsofseacucumbers

(D)threatstoseacucumbers'existence

13.Thephrase"castsoff"inline24isclosestin

meaningto

(A)growsagain

(B)grabs

(C)getsridof

(D)usesasaweapon

14.Ofallthecharacteristicsoftheseacucumber,

whichofthefollowingseemstofascinatethe

authormost?

(A)Whatitdoeswhenthreatened

(B)Whereitlives

(C)Howithidesfrompredators

(D)Whatiteats

15.Comparedwithotherseacreaturesthesea

cucumberisvery

(A)dangerous

(B)intelligent

(C)strange

(D)fat

16.Whatcanbeinferredaboutthedefense

mechanismsoftheseacucumber?

(A)Theyareverysensitivetosurrounding

stimuli.

(B)Theyarealmostuseless.

(C)Theyrequiregroupcooperation.

(D)Theyaresimilartothoseofmostsea

creatures.

17.WhichofthefollowingwouldNOTcauseasea

cucumbertoreleaseitsinternalorgansintothe

water?

(A)Atouch

(B)Food

(C)Unusuallywarmwater

(D)Pollution

18.Whichofthefollowingisanexampleof

behaviorcomparablewiththeseacucumber

livingatalowmetabolicrate?

(A)Anoctopusdefendingitselfwithitstentacles

(B)Abearhibernatinginthewinter

(C)Apigeatingconstantly

(D)Aparasitelivingonitshost'sblood

Exampletwo:(没讲)

ElizabethHazenandRachelBrowncopatentedoneofthemostwidelyacclaimed

wonderdrugsofthepost-SecondWorldWaryears.HazenandBrown'sworkwas

stimulatedbythewartimeneedtofindacureforthefungusinfectionsthatafflicted

manymilitarypersonnel.Scientistshadbeenfeverishlysearchingforanantibiotic

5)toxicenoughtokillthefungibutsafeenoughforhumanuse,since,unfortunately,

the

new"wonderdrugs"suchaspenicillinandstreptomycinkilledtheverybacteriain

the

bodythatcontrolledthefungi.Itwastodiscoverafungicidewithoutthatdouble

effect

thatBrown,ofNewYorkState'sDepartmentofHealthinNewYork,begantheir

Hazen,seniormicrobiologistattheDepartmentofHealthinLaboratoriesatAlbany,

and

10)long-distancecollaboration.BaseduponHazen'spreviousresearchatColumbia

University,whereshehadbuiltanimpressivecollectionoffunguscultures,both

were

convincedthatanantifungalorganismalreadyexistedincertainsoils.

Theydividedthework.Hazenmethodicallyscreenedandculturedscoresofsoil

samples,whichshethensenttoherpartner,whopreparedextracts,isolatedand

15)purifiedactiveagents,andshippedthembacktoNewYork,whereHazencould

study

theirbiologicalproperties.Ona1948vacation.Hazenfortuitouslycollectedaclump

of

soilfromtheedgeofW.B.Nourse'scowpastureinFauquierCounty.Virginia,that,

whentested,revealedthepresenceofthemicroorganisms,InfarmownerNourse's

honor,HazennameditStreptomycesnoursei,andwithinayearthetwoscientists

knew

20)thatthepropertiesoftheirsubstancedistinguisheditfrompreviouslydescribed

antibiotics.Afterfurtherresearchtheyeventuallyreducedtheirsubstancetoafine,

yellowpowder,whichtheyfirstnamed"fungiciden/*thenrenamed"nystatin"

(tohonortheNewYorkStatelaboratory)whentheylearnedthepreviousnamewas

alreadyinuse.Oftheirmajordiscovery,Brownsaidlightlythatitsimplyillustrated

"howunpredictableconsequencescancomefromrathermodestbeginnings."

45.Whatisthemaintopicofthepassage?

(A)ThelivesofHazenandBrown.

(B)Thedevelopmentofasafefungicide.

(C)TheNewYorkStateDepartmentofHealth.

(D)Thedevelopmentofpenicillin.

46.Whatcanbeinferredfromthepassageabout

penicillin?

(A)Iteffectivelytreatsfungusinfections.

(B)Itwasdevelopedbeforenystatin.

(C)ItwasdevelopedtheSecondWorldWar.

(D)Oneoftheby-productsisnystatin.

47.WhydoestheauthormentionColumbia

Universityinlines10and11?

(A)HazenandBrowndevelopednystatinthere.

(B)Brownwaseducatedthere.

(C)Hazendidresearchthere.

(D)ItawardedaprizetoHazenandBrown.

48.Theword"both"inline11refersto

(A)HazenandBrown

(B)Penicillinandstreptomycin

(C)theDepartmentofHealthlaboratoriesat

AlbanyandNewYork

(D)doubleeffect

49.WhatsubstancedidBrownandHazen

analyze?

(A)Dirt

(B)Streptomycin

(C)Penic川in

(D)Bacteria

50.WhowasW.B.Bourse?

(A)Amicrobiologist

(B)AteacherofHazen's

(C)Acollectoroffungi

(D)Afarmer

Examplethree:(没讲)

Fungi,ofwhichthereareover100,000species,includingyeastsandother

single-celledorganismsaswellasthecommonmoldsandmushrooms,were

formerlyclassifiedasmembersoftheplantkingdom.However,inrealitytheyare

Lineverydifferentfromplantsandtodaytheyareplacedinaseparategroup

altogether.

(5)Theprincipalreasonforthisisthatnoneofthempossesseschlorophyll,and

since

theycannotsynthesizetheirowncarbohydrates,theyobtaintheirsupplieseither

fromthebreakdownofdeadorganicmatterorfromotherlivingorganisms.

Furthermorethewallsoffungalcellsarenotmadeofcellulose,asthoseofplants

are,butofanothercomplexsugarlikepolymercalledchitin,thematerialfromwhich

(10)thehardouterskeletonsofshrimps,spiders,andinsectsaremade.The

difference

betweenthechemicalcompositionofthecellwallsoffungiandthoseofplants

isofenormousimportancebecauseitenablesthetipsofthegrowinghyphae,the

threadlikecellsofthefungus,tosecreteenzymesthatbreakdownthewallsofplant

cellswithouthavinganyeffectonthoseofthefungusitself.Itisthesecellulose-

(15)destroyingenzymesthatenablefungitoattackanythingmadefromwood,

wood

pulp,cotton,flax,orotherplantmaterial.

Thedestructivepoweroffungiisimpressive.Theyareamajorcauseofstructural

damagetobuildingtimbers,acauseofdiseaseinanimalsandhumans,andoneof

thegreatestcausesofagriculturallosses.Entirecropscanbewipedoutbyfungal

(20)attacksbothbeforeandafterharvesting.Somefungicangrowat+50°C,while

otherscangrowat-5°C,soevenfoodincoldstoragemaynotbecompletelysafe

fromthem.Ontheotherhand,fungibringaboutthedecompositionofdeadorganic

matter,thusenrichingthesoilandreturningcarbondioxidetotheatmosphere.

They

alsoenterintoanumberofmutuallybeneficialrelationshipswithplantsandother

(25)organisms.Inaddition,fungiarethesourceofmanyofthemostpotent

antibiotics

usedinclinicalmedicine,includingpenicillin.

11.Whatdoesparagraph1mainlydiscuss?

(A)Differencesbetweensimplyandcomplex

fungi

(B)Functionsofchlorophyllinplants

(C)Functionsofsugarinthewallsoffungal

cells

(D)Differencesbetweenfungiandplants

12.Whichofthefollowingismentionedasamajor

changeinhowscientistsapproachthestudyof

fungi?

(A)Fungiarenolongerclassifiedasplants.

(B)Somesingle-cellorganismsarenolonger

classifiedasfungi.

(C)Newmethodsofspeciesidentificationhave

beenintroduced.

(D)Theoriesaboutthechemicalcompositionof

fungihavebeenrevised.

13.Theword"principal"inline5isclosestin

meaningto

(A)true

(B)main

(C)logical

(D)obvious

14.Accordingtothepassage,howdofungiobtain

carbohydrates?

(A)Theyabsorbcarbohydratesfromtheirown

cellwalls.

(B)Theysynthesizechlorophylltoproduce

carbohydrates.

(C)Theyproducecarbohydratesbybreaking

downchitin.

(D)Theyacquirecarbohydratesfromother

organicmatter,bothlivinganddead.

15.Thepassagementionsshrimps,spiders,and

insectsinline10becausetheirskeletons

(A)canbedestroyedbyfungi

(B)haveunusualchemicalcompositions

(C)containamaterialfoundinthewallsof

fungalcells

(D)secretethesameenzymesasthewallsof

fungalcellsdo

16.Whichofthefollowingtermsisdefinedinthe

passage?

(A)"chlorophyll"(Iine5)

(B)"polymer',(Iine9)

(C)"hyphae"(Iinel2)

u

(D)enzymes"(Iinel3)

17.Theword"those"inline14refersto

(A)tips

(B)hyphae

(C)enzymes

(D)walls

18.Fungihaveallofthefollowingcharacteristics

EXCEPT:

(A)Theygrowhyphae.

(B)Theysecreteenzymes.

(C)Theysynthesizecellulose.

(D)Theydestroycrops.

19.Theword"Entire"inline19isclosestin

meaningto

(A)certain

(B)whole

(C)mature

(D)diseased

20.Thepassagedescribesthenegativeeffectsof

fungionallofthefollowingEXCEPT

(A)buildings

(B)animals

(C)food

(D)soil

21.Thephrase"bringabout"inline22isclosestin

meaningto

(A)cause

(B)join

(C)take

(D)include

22.Thepassagementions"penicillin"inline26as

anexampleof

(A)amedicinederivedfromplants

(B)abeneficialuseoffungi

(C)aproductoftherelationshipbetweenplants

andfungi

(D)atypeoffungithatgrowsatextreme

temperatures.

Passage1:

WhenJulesVernewroteJourneytotheCenteroftheEarthin1864,therewere

manyconflictingtheoriesaboutthenatureoftheEarth'sinterior.Somegeologists

thoughtthatitcontainedahighlycompressedballofincandescentgas,whileothers

Linesuspectedthatitconsistedofseparateshells,eachmadeofadifferentmaterial.

Today,

(5)welloveracenturylater,thereisstilllittledirectevidenceofwhatliesbeneath

our

feet.MostofourknowledgeoftheEarth'sinteriorcomesnotfromminesor

boreholes,

butfromthestudyofseismicwaves-powerfulpulsesofenergyreleasedby

earthquakes.

ThewaythatseismicwavestravelshowsthattheEarth*sinteriorisfarfrom

(lO)uniform.Thecontinentsandtheseabedareformedbythecrust-athinsphere

of

relativelylight,solidrock.Beneaththecrustliesthemantle,averydifferentlayer

that

extendsapproximatelyhalfwaytotheEarth'scenter.Theretherockisthesubject

ofa

battlebetweenincreasingheatandgrowingpressure.

Initshighlevels,themantleisrelativelycool;atgreaterdepths,hightemperatures

(15)maketherockbehavemorelikealiquidthanasolid.Deeperstill,thepressure

iseven

moreintense,preventingtherockfrommeltinginspiteofahighertemperature.

Beyondadepthofaround2,900kilometers,agreatchangetakesplaceandthe

mantlegiveswaytothecore.Someseismicwavescannotpassthroughthecore

and

othersarebentbyit.Fromthisandotherevidence,geologistsconcludethatthe

outer

(20)coreisprobablyliquid,withasolidcenter.Itisalmostcertainlymadeofiron,

mixed

withsmalleramountsofotherelementssuchasnickel.

TheconditionsintheEarth'scoremakeitafarmorealienworldthanspace.Its

solidironheartissubjectedtounimaginablepressureandhasatemperatureof

about

9.000°F.Althoughscientistscanspeculateaboutitsnature,neitherhumansnor

machinesw川everbeabletovisitit.

l.Theword"conflicting"inline2isclosestinmeaningto

(A)controlling

(B)outdated

(C)opposing

(D)important

2.Whatistoday'srichestsourceofinforma-tionabouttheEarth'sinteriorfor

geologis-ts?

(A)Boreholes

(B)Shells

(C)Seismicwaves

(D)Mines

3.Theword"There"inline12referstothe

(A)mantle

(B)crust

(C)seabed

(D)Earth'scenter

4.WhichofthefollowingisaprimarycharacteristicoftheEarth'smantle?

(A)Light,solidrock

(B)Uniformityofcomposition

(C)Dramaticallyincreasingpressure

(D)Compressed,incandescentgas

5.Thephrase"giveswayto"inline18isclosestinmeaningto

(A)runsalong

(B)rubsagainst

(C)turnsinto

(D)floatson

6.Theword"it"inline19refersto

(A)mantle

(B)core

(C)change

(D)depth

7.Whydoestheauthorstateinline22thattheEarth'scoreis"morealien"than

space?

(A)GovernmentfundsarenotavailabletostudytheEarth'score.

(B)Scientistsaren'tinterestedinthecharacteristicsoftheEarth'score.

(C)ItisimpossibletogototheEarth'scoretodoresearch.

(D)TheEarth'scoreismadeofelementsthatare

8.Theword"speculate"inline24isclosestinmeaningto

(A)report

(B)learn

(C)worry

(D)hypothesize

Passage2

Theoceanbottom——aregionnearly2.5timesgreaterthanthetotallandareaof

the

Earth——isavastfrontierthateventodayislargelyunexploredanduncharted.

Until

aboutacenturyago,thedeep-oceanfloorwascompletelyinaccessible,hidden

beneath

watersaveragingover3,600metersdeep.Totallywithoutlightandsubjectedto

intense

(5)pressureshundredsoftimesgreaterthanattheEarth'ssurface,thedeep-ocean

bottom

isahostileenvironmenttohumans,insomewaysasforbiddingandremoteasthe

void

ofouterspace.

Althoughresearchershavetakensamplesofdeep-oceanrocksandsedimentsfor

overacentury,thefirstdetailedglobalinvestigationoftheoceanbottomdidnot

(lO)actuallystartuntil1968,withthebeginningoftheNationalScience

Foundation'sDeep

SeaDrillingProject(DSDP).Usingtechniquesfirstdevelopedfortheoffshoreoiland

gasindustry,theDSDP'sdrillship,theGlomarChallenger,wasabletomaintaina

steadypositionontheocean'ssurfaceanddrillinverydeepwaters,extracting

samples

ofsedimentsandrockfromtheoceanfloor.

(15)TheGlomarChallengercompleted96voyagesina15-yearresearchprogram

that

endedinNovember1983.Duringthistime,thevessellogged600,000kilometers

and

tookalmost20,000coresamplesofseabedsedimentsandrocksat624drillingsites

aroundtheworld.TheGlomarChallenger'scoresampleshaveallowedgeologists

toreconstructwhattheplanetlookedlikehundredsofmillionsofyearsagoandto

(20)calculatewhatitwillprobablylooklikemillionsofyearsinthefuture.Today,

largely

onthestrengthofevidencegatheredduringtheGlomarChallenger'svoyages,

nearly

allearthscientistsagreeonthetheoriesofplatetectonicsandcontinentaldriftthat

explainmanyofthegeologicalprocessesthatshapetheEarth.

ThecoresofsedimentdrilledbytheGlomarChallengerhavealsoyielded

(25)informationcriticaltounderstandingtheworld'spastclimates.Deep-ocean

sediments

provideaclimaticrecordstretchingbackhundredsofmillionsofyears,because

they

arelargelyisolatedfromthemechanicalerosionandtheintensechemicaland

biological

activitythatrapidlydestroymuchland-basedevidenceofpastclimates.Thisrecord

has

alreadyprovidedinsightsintothepatternsandcausesofpastclimaticchange-

informationthatmaybeusedtopredictfutureclimates.

l.Theauthormentionsouterspaceinline7because

(A)theEarth'sclimatemillionsofyearsagowassimilartoconditionsinouterspace

(B)itissimilartotheoceanfloorinbeingalientothehumanenvironment

(C)rockformationsinouterspacearesimilartothosefoundontheoceanfloor

(D)techniquesusedbyscientiststoexploreouterspaceweresimilartothoseused

inoceanexploration

Passage3

Despitetheroadimprovementsoftheturnpikeera(1790-1830),Americans

continuedasincolonialtimestodependwhereverpossibleonwaterroutesfor

travel

andtransportation.Thelargerrivers,especiallytheMississippiandtheOhio,

became

Lineincreasinglyusefulassteamboatsgrewinnumberandimprovedindesign.

(5)RiverboatscarriedtoNewOrleansthecornandothercropsofnorthwestern

farmers,thecottonandtobaccoofsouthwesternplanters.FromNewOrleans,ships

tookthecargoesontoeasternseaports.Neitherthefarmersofthewestnorthe

merchantsoftheeastwerecompletelysatisfiedwiththispatternoftrade.Farmers

couldgetbetterpricesfortheircropsifthealternativeexistedofsendingthem

directly

(lO)eastwardtomarket,andmerchantscouldselllargerquantitiesoftheir

manufactured

goodsifthesecouldbetransportedmoredirectlyandmoreeconomicallytothewest.

Newwaterwayswereneeded.Sectionaljealousiesandconstitutionalscruplesstood

inthewayofactionbythefederalgovernment,andnecessaryexpenditureswere

too

greatforprivateenterprise.Ifextensivecanalsweretobedug,thejobwouldbeup

to

(15)thevariousstates.

NewYorkwasthefirsttoact.Ithadthenaturaladvantageofacomparativelylevel

routebetweentheHudsonRiverandLakeErie,throughtheonlybreakintheentire

AppalachianMountainchain.Yettheengineeringtaskswereimposing.Thedistance

wasmorethan350miles,andtherewereridgestocrossandawildernessofwoods

and

(20)swampstopenetrate.TheErieCanal,begunin1817andcompletedin1825,

wasbyfar

thegreatestconstructionjobthatAmericanshadeverundertaken.Itquicklyproved

a

financialsuccessaswell.TheprosperityoftheErieencouragedthestatetoenlarge

its

canalsystembybuildingseveralbranches.

(20)TherangeoftheNewYorkcanalsystemwasstillfurtherextendedwhenthe

states

ofOhioandIndiana,inspiredbythesuccessoftheErieCanal,providedwater

connectionsbetweenLakeErieandtheOhioRiver.

9.Whatdoesthepassagesuggestwastheprincipalroutefortransportingcropsto

theeastpriorto1825?

(A)Rivertoroad

(B)Canaltoriver

(C)Rivertoocean

(D)Roadtocanal

10.ItcanbeinferredfromthepassagethatshippingcargoeastbywayofNew

Orleanswas

(A)advantageousformanufacturers

(B)inexpensiveformerchants

(C)noteconomicalforfarmers

(D)consideredeconomicalbythegovernment

11.Theword"alternative"inline9isclosestinmeaningto

(A)option

(B)transition

(C)intention

(D)authorization

12.Theword"them"inline9refersto

(A)crops

(B)farmers

(C)prices

(D)merchants

13.Whichofthefollowingproductswouldanorthwesternfarmerintheearly

nineteenthcenturybemostlikelytopurchasefromtheeast?

(A)Grain

(B)Vegetables

(C)Textiles

(D)Fruit

14.Accordingtothepassage,wherewastheErieCanallocated?

(A)BetweenOhioandIndiana

(B)AlongtheAppalachianMountains

(C)BetweenLakeErieandtheOhioRiver

(D)AcrossNewYorkState

15.Theword"imposing"inline18couldbestbereplacedby

(A)impractical

(B)successful

(C)demanding

(D)misleading

16.Theword"penetrate"inline20isclosestinmeaningto

(A)cutdown

(B)gothrough

(C)fillup

(D)takeover

17.Theword"its"inline22refersto

(A)prosperity

(B)Erie

(C)system

(D)state

18.Theword"extended"inline24isclosestinmeaningto

(A)increased

(B)constructed

(C)deepened

(D)measured

19.Accordingtothepassage,IndianaandOhiosupportedthedevelopmentofthe

NewYorkcanalsystemby

(A)helpingtobuildtheErieCanal

(B)buildingbranchestoconnectitwiththeOhioRiver

(C)providingmuchofthewaterfortheErieCanal

(D)contributingfinanciallytotheconstructioncosts

20.Whatdoestheparagraphfollowingthepassageprobablydiscuss?

(A)IndustryonLakeErie

(B)CanalsinOhioandIndiana

(C)SectionaljealousiesinIndianaandOhio

(D)TravelontheErieCanal4.

Passage4

LegendhasitthatsometimetowardtheendoftheCivilWar(1861-1865)a

governmenttraincarryingoxentravelingthroughthenorthernplainsofeastern

Wyomingwascaughtinasnowstormandhadtobeabandoned.Thedriverreturned

the

Linenextspringtoseewhathadbecomeofhiscargo.Insteadoftheskeletonshe

had

(5)expectedtofind,hesawhisoxen,living,fat,andhealthy.Howhadthey

survived?

TheanswerlayinaresourcethatunknowingAmericanshadtrampledunderfootin

theirhastetocrossthe"GreatAmericanDesert"toreachlandsthatsometimes

proved

barren.IntheeasternpartsoftheUnitedStates,thepreferredgrassforforagewas

a

cultivatedplant.Itgrewwellwithenoughrain,thenwhencutandstoreditwould

cure

(10)andbecomenourishinghayforwinterfeed.Butinthedrygrazinglandsofthe

West,

thatfamiliarbluejointgrasswasoftenkilledbydrought.Toraisecattleoutthere

seemedriskyorevenhopeless.

Whocouldimagineafairy-talegrassthatrequirednorainandsomehowmadeit

possibleforcattletofeedthemselvesallwinter?Butthesurprisingwesternwild

(15)grassesdidjustthat.Theyhadwonderfullyconvenientfeaturesthatmade

them

superiortothecultivatedeasterngrasses.Variouslyknownasbuffalograss,grama

grass,ormesquitegrass,notonlyweretheyimmunetodrought;buttheywere

actually

preservedbythelackofsummerandautumnrains.Theywerenotjuicylikethe

cultivatedeasterngrasses,buthadshort,hardstems.Andtheydidnotneedtobe

cured

(20)inabarn,butdriedrightwheretheygrewontheground.Whentheydriedin

thisway,

theyremainednaturallysweetandnourishingthroughthewinter.Cattleleft

outdoors

tofendforthemselvesthrivedonthishay.Andthecattlethemselveshelpedplant

the

freshgrassyearafteryear,fortheytrampledthenaturalseedsfirmlyintothesoil

tobe

wateredbythemeltingsnowsofwinterandtheoccasionalrainsofspring.Thedry

(25)summeraircuredthem,muchasstoringinabarncuredthecultivatedgrasses.

21.Whatdoesthepassagemainlydiscuss?

(A)WesternmigrationaftertheCivilWar

(B)TheclimateofthewesternUnitedStates

(C)Theraisingofcattle

(D)Atypeofwildvegetation

22.Whatcanbeinferredbythephrase"Legendhasit"inline1?

(A)Thestoryofthetrainmaynotbecompletelyfactual.

(B)Mosthistorybooksincludethestoryofthetrain.

(C)Thedriverofthetraininventedthestory.

(D)Thestoryofthetrainissimilartootheronesfromthattimeperiod.

23.Theword"they"inline5refersto

(A)plains

(B)skeletons

(C)oxen

(D)Americans

24.Whatcanbeinferredaboutthe"GreatAmericanDesert"mentionedinline7?

(A)Itwasnotoriginallyassumedtobeafertilearea.

(B)Manyhadsettledtherebythe1860's.

(C)ItwasapopularplacetoraisecattlebeforetheCivilWar.

(D)Itwasnotdiscovereduntilthelate1800's.

25.Theword"barren"inline8isclosestinmeaningto

(A)lonely

(B)dangerous

(C)uncomfortable

(D)infertile

26.Theword"preferred"inline8isclosestinmeaningto

(A)ordinary

(B)available

(C)required

(D)favored

27.Whichofthefollowingcanbeinferredaboutthecultivatedgrassmentionedin

thesecondparagraph?

(A)CattleraisedinthewesternUnitedStatesrefusedtoeatit.

(B)ItwouldprobablynotgrowinthewesternUnitedStates.

(C)IthadtobeimportedintotheUnitedStates.

(D)Itwasdifficultforcattletodigest.

28.WhichofthefollowingwasNOToneofthenamesgiventotheWesterngrasses?

(A)Gramagrass

(B)Bluejointgrass

(C)Buffalograss

(D)Mesquitegrass

29.WhichofthefollowingwasNOTmentionedasacharacteristicofwesterngrasses?

(A)Theyhavetoughstems

(B)Theyarenotaffectedbydryweather

(C)The