托福模拟考试及答案解析八

托福模拟考试及答案解析（8）

（1~13/共52题乂却读理解

THENORSEINNORTHAMERICA

1TheNorsemadethefirstdocumentedEuropeanvoyagestoNorthAmerica,andthereis

evidenceofthesevisitsinthemedievalsagas,acollectionofstoriesthattellthehistoryofthe

Icelandicpeople.TheIcelandicsagasrelatehowtheNorsecaptainLeifErikssonandhisbrother

sailedfromNorwaytoGreenlandandlandedtothewestofGreenland.Thesagasalsodescribe

ThorfinnKarlsefni'sattempttocolonizeaplacecalledVinland.Althoughsomehistoriansdoubt

theiraccuracy,thesagasareasourceofintriguingdetails,anduntilthetwentiethcenturythey

weretheprimarysourceofinformationabouttheNorseexplorationofNorthAmerica.

2Inthetenthcentury,NorsemenventuredfromtheirhomelandinScandinaviatobuild

settlementsontheGreenlandcoast.AtradernamedBjarniHerjolfssonsailedforGreenlandin

thesummerof985or986.Drivenoffcoursebyastorm,hesubsequentlydiscoveredacoastline

hedescribedaswoodedandhilly.AlthoughBjarnididnotgoashore,thisdiscoverymadehimthe

firstEuropeantoseteyesonthecontinentofNorthAmerica.Bjarni'saccountofhisvoyage

encouragedanotherNorseman,LeifEriksson,toundertakeasouthwardvoyage,startingaround

theyear1000,withacrewof35men.

3Accordingtothesagas,LeifErikssonandhismenfirstlandedinaplacetheycalled

Stoneland,whichwasprobablytherocky,barrenLabradorcoastofNorthAmerica.Theparty

finallylandedinaplacetheycalledVinland,wheretheyspentawinterinroughhutsina

seeminglyfrost-freelandofabundantvinesandwildgrapes.TheyestablishedthefirstEuropean

colonyinNorthAmericaatVinland,thepreciselocationofwhichremainsasubjectofscholarly

disputetothisday.TheNorsemenreturnedhomeinthespring,abandoningtherudesettlement

that,afewyearslater,wouldserveashomebaseforThorfinnKarlsefniofGreenland.

4Around1004,theexpeditionledbyThorfinnsetoffsouthward,evidentlywithalongerstay

inmind,aswomenandcattleaccompaniedthesailorsinthreeships.Thepartyof160made

severallandingsandeventuallyfoundaplacewithvines,wheretheysettledatasiteupariver

thatwidenedintoalake.TheypassedtwoyearsatVinland,exploringthecoast,buildinghuts,

fishing,andgatheringnativefoods.Duringthattime,Thorfinn'swifegavebirthtoaboy,thefirst

childofEuropeandescentbornintheAmericas.Thesettlershadseveralhostileencounterswith

thelocalaboriginaltribes,whomtheycalled"skrelings."Inonefightwithanativegroup,

ThorfinnandanotherNorsemanwerekilled.Thecontinuingprospectofattackandgrowing

dissensioninthesettlementmayhavethwartedtheNorseattemptatcolonization.Forsome

reason,theydepartedtheirsettlement;however;Greenlanderscontinuedtomakeoccasional

visitsthereinlateryears,usingitasafishingcamp.Historianshavemademanyattemptsto

identifythelandsvisitedbyThorfinnandtodiscoverhiscampsites,butnosingletheoryhaswon

generalacceptance.

5Inthetwentiethcentury,theIcelandicsagasservedasinspirationforNorwegianexplorer

andwriterHelgeIngstad,whointheearly1960straveledthecoastsofeasternNorthAmerica

searchingforevidenceofVinland.Encouragedbyanalternativeinterpretationof"vin"as

meaning"meadow"ratherthanvineorwine,Ingstaddiscoveredagrassysiteonthenortherntip

ofNewfoundlandthatlocalpeoplehadbelievedwasanaboriginalsitehauntedbyancientghosts.

Ingstadexcavatedtheremainsofeightsodhuts,togetherwithbronzeandstonetoolsofNorse

origin.HeconcludedthatthegrasslandcalledL'AnseauxMeadowswas,ifnottheVinlandofthe

sagas,thencertainlyaNorsesettlementofsomekind.

6Huddledforprotectionfromthewind,theclusterofsod-builtstructuresatL'Anseaux

Meadowswasnotemporarycamp.Sodwallsandsodroofsbuiltoveratimberframeindicated

dwellingsthatweresubstantialenoughforpermanentoccupation.Theeighthutsincludedthree

long,narrowbuildingswithfeaturessimilartothosefoundinNorsestructuresinGreenlandand

Iceland.Thelargestofthesemeasured29by15metersandconsistedofseveralrooms.Smaller

buildings,probablyusedforstorageandworkshops,includedaforgethatusedironoreextracted

frompeatbogs-evidenceofthefirstironworkinginNorthAmerica.Alsoamongtheartifacts

wereaspindleandaboneknittingneedle,suggestingthepresenceofwomeninthesettlement.

Glossary:

sod:soilheldtogetherbytherootsofgrass

第1题

Whatcanbeinferredfromparagraph1abouttheIcelandicsagas?

A.TheywerenotknownoutsideofIceland.

B.Theywereoriginallytoldintheformofsongs.

C.Theymaynotbehistoricallyaccurate.

D.TheyinspiredLeifErikssontoexploreVinland.

第2题

Thephraseseteyesoninparagraph2isclose,inmeaningto

A.colonize

B.observe

C.imagine

0.explore

第3题

Accordingtothepassage,whowasprobablythefirstEuropeantosteponthecontinentofNorth

America?

A.BjarniHerjolfsson

B.LeifEriksson

C.ThorfinnKarlsefni

D.HelgeIngstad

第4题

Thewordabundantinparagraph3isclosestinmeaningto

A.numerous

B.tropical

C.familiar

D.poisonous

第5题

Whichsentencebelowbestexpressestheessentialinformationinthehighlightedsentencein

paragraph3?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessential

information.

A.TheNorsewerethefirstEuropeanstodiscoverNorthAmerica,butlittleevidenceremainsof

theirsettlementatVinland.

B.ThelocationofVinland,thefirstEuropeancolonyinNorthAmerica,wasunknownuntilthe

twenty-firstcentury.

C.TheEuropeanschoseVinlandasthesiteoftheirfirstcolonybecauseithadperfectconditions

forgrowinggrapes.

D.Eriksson'sVinlandwasthefirstEuropeancolonyinNorthAmerica,butscholarsstilldisagree

overexactlywhereitwas.

第6题

Whydoestheauthormentionwomenandcattleinparagraph4?

A.Toshowthelevelofdetailincludedinthesagas

B.Tbpointoutthepeacefulintentionsofthesailors

C.Toprovideevidenceofaplantostartacolony

D.TodescribethedivisionoflaborinNorsesociety

第7题

Thewordthwartedinparagraph4isclosestinmeaningto

A.preceded

B.ended

C.concealed

□.inspired

第8题

WhatbecameofVinlandafterThorfinnKarlsefni'spartyleft?

A.Hostilenativetribesdestroyedthebuildings.

B.ltbecameapermanentcolonyafewyearslater.

C.Historiansmadenofurthermentionofit.

D.ltwassometimesusedasabaseforfishing.

第9题

WhatledtothediscoveryatL'AnseauxMeadowsinthe1960s?

A.TheaccountofVinland'swildgrapesinthesagas

B.Thesearchforafavorableplaceforacolony

C.TheideathatVinlandreferredtoameadow

D.Theinterestinwritingaboutahauntedplace

第10题

Thewordsubstantialinparagraph6isclosestinmeaningto

A.large

B.complex

C.strong

□.comfortable

第11题

Paragraphs5and6supportwhichofthefollowingstatementsaboutthesiteatL'Anseaux

Meadows?

A.ThestructuresandartifactsaresoundevidenceofaNorsecolony.

B.TheNorseandtheaboriginalpeoplebuiltsimilartypesofdwellings.

C.ThesitecouldnothavebeenVinlandbecausetherewerenonativevines.

D.TheNorseculturewasmoreadvancedthanhistorianshadoncebelieved.

第12题

Lookatthefoursquares,A,B,C,andD,whichindicatewherethefollowingsentencecouldbe

addedtothepassage.Wherewouldthesentencebestfit?

TheythensailedsouthtoWoodland,whichcouldhavebeenNewfoundland,NovaScotia,or

Maine,allofwhicharewooded.

AAccordingtothesagas,LeifErikssonandhismenfirstlandedinaplacetheycalledStoneland,

whichwasprobablytherocky,barrenLabradorcoastofNorthAmerica.BThepartyfinallylanded

inaplacetheycalledVinland,wheretheyspentawinterinroughhutsinaseeminglyfrost-free

landofabundantvinesandwildgrapes.CTheyestablishedthefirstEuropeancolonyinNorth

AmericaatVinland,thepreciselocationofwhichremainsasubjectofscholarlydisputetothis

day.DTheNorsemenreturnedhomeinthespring,abandoningtherudesettlementthat,afew

yearslater;wouldserveashomebaseforThorfinnKarlsefniofGreenland.

第13题

Anintroductorysentenceforabriefsummaryofthepassageisprovidedbelow.Completethe

summarybyselectingtheTHREEanswerchoicesthatexpressthemostimportantideasinthe

passage.Somesentencesdonotbelonginthesummarybecausetheyexpressideasthatarenot

presentedinthepassageorareminorideasinthepassage.Thisquestionisworth2point.

EvidencesuggeststhattheNorsewerethefirst

EuropeanswhoattemptedtocolonizeNorthAmerica.

AnswerChoices

A.TheIcelandicsagasdocumentthevoyagesofNorsemenwholandedinNorthAmericaand

exploredthecoast.

B.ThetraderBjarniHerjolfssonwassailingforGreenlandwhenhewasblownoffcourseby

stormyweather.

C.LeifErikssondiscoveredaplacecalledVinland,andThorfinnKarlsefnilaterestablisheda

settlementthere.

D.Norsemantraveledbyshiptodistantlandswiththepurposeofconqueringnativepeoplesand

takingtheirland.

E.EarlyNorsesettlersinNorthAmericahadseveralviolentencounterswithnativetribes,sothey

didnotstaylong.

F.ManysignsofanearlyNorsesettlementhavebeendiscoveredatagrassymeadowin

Newfoundland.

下一题

（14~26/共52题）阅读理解

THEFIVE-SEVENSHIFT

1Allmajortheoriesofchildpsychologystatethatchildrenundergoamajorchangebetween

theagesoffiveandseven.Inclassicallearningtheory,thisisatimewhenthesimplestformsof

learninggivewaytolearningthatinvolvesmorecomplexmentalprocesses.Accordingto

psychologistJeanPiaget,theperiodfromfivetosevenyearsoldisatransitiontooperational

thought,whenchildrenareabletomovebeyondusingonlytheirsensestowardusinganewset

ofrational-thinkingskills.Becauseseveralcognitivechangesoccurinchildrenbetweenagesfive

andseven,thisperiodiscalledthefive-sevenshift.Theshiftisbiologicalinnatureandinvolves

fundamentalgrowthinthebrainandstabilizationofbrain-waverhythmsintoabasicallyadult

pattern.Thefive-sevenshiftinvolvesmanyphysicalchanges,suchasthelossofthe"babyteeth"

andanincreaseintheratesofheightacquiredandweightgained.

2Bythetimetheyarefiveyearsold,childrencanunderstandandusesymbols.Theyhave

developedtheabilitytousewords,gestures,andpicturestostandfor"reallife"objects,andthey

areskilledindeployingvarioussymbolsystems,suchaslanguageordrawing.However,a

five-year-oldchildisabletofocusattentionononlyonequalityofanobjectatatime,suchasthe

object'ssizeorshape.Theuseofsymbolizationcontinuestoevolve,reachingapeakaroundthe

ageofsevenoreight,whenchildrenbecomecapableofconcreteoperations.Whenthishappens,

theycansolveproblemsbyusingrationalthoughttomakegeneralizationsfromtheirown

experience.

3Bytheageofsevenoreight,anewsetofabilitiesallowschildrentoreasonsystematically

abouttheworldofobjects,quantity,time,space,andcausality.AccordingtoPiaget,thisis

becausean"extracard"isaddedtothechild'smental"computer"duringthefive-sevenshift.The

developmentofoperationalthoughtenablesthechildtoappreciatetherelationsamongaseries

ofactionsuponobjects.Forexample,thechildunderstandsthatascenecanbeviewedfroma

differentperspectiveandstillcontainthesameelements.Thechildalsounderstandsthatobjects

canberearrangedandstillhavethesamequantityandthatasubstancecanbechangedinshape

withoutitsmassorvolumebeingaffected.

4Piagetdiscoveredthemostwidelyknownhallmarkofthefive-sevenshift,anunderstanding

ofconservation,theideathatsomepropertiesstaythesamedespitechangesinappearance.In

oneofPiaget'sclassicexperimentsontheconservationofquantity,theexperimentershows

childrenofdifferentagestwostraightrowsofcoins,eachwithsixcoinspressedclosetogether,

besideeachotheronatable.Theexperimenteraskseachchildsubjectwhetherbothrowshave

thesamenumberofcoinsorwhetheronerowhasmore.Thentheexperimenterspreadsoutthe

coinsofonerowtomakethelinelooklonger.Thechildmustnowsaywhetheronerowhasmore

coins.Childrenyoungerthanfiveyearsoldcannotunderstandconservation,sotheyinvariably

saythatthespread-outrowhasmorecoinsthantheotherrow.

5Likemostage-relatedtasksforchildren,thereareotherwaystosetupthetask.Inasimilar

experiment,waterispouredintotwoidenticalglassesuntilthechildsubjectagreesthateach

containsanequalamount.Thentheexperimenterpourswaterfromoneoftheseglassesintoa

tall,thinglass.Atthatpoint,thechildisaskedwhetheroneglasshasmorewaterthantheother.

Five-year-oldchildrenwillsaythatthereismorewaterinthetail,thinglass.Whenaskedwhy

theythinkthat,manywillconfidentlysay,"Becauseit'staller,"Olderchildren,however,arelikely

toreply,"Itlookslikethere'smorewaterinthisonebecauseit'staller;butthey'rereallythe

same."Suchexperimentsshowadifferencebetweenchildrenoffiveyearsandchildrenofeight

years.Theolderchildrencansolvethetaskpromptly,easily,underawidevarietyofconditions,

andwithoutbeingtaught.Theyoungerchildren,eveniftheyaretaughtaboutconservation,

cannotdowhatthefive-sevenshiftwilldoforthemnaturally:providethemwithamore

developedbrain.

Glossary:

cognitive:relatingtomentalprocesses

第14题

Thephrasegivewaytoinparagraph1isclosestinmeaningto

A.include

B.follow

C.become

□.replace

第15题

Accordingtothepassage,childrenbetweentheagesoffiveandseventypicallyexperienceallof

thefollowingEXCEPT

A.developmentofrationalthinking

B.aninterestinmoralityandrules

C.importantchangesinthebrain

D.anincreaseinthephysicalgrowthrate

第16题

Whatcanbeinferredfromparagraph1aboutcognitivedevelopmentduringthefive-sevenshift?

A.Itisatimewhenchildrenstartlearninginverysimpleways.

B.ltisthemostimportantperiodinthechild'sformaleducation.

C.ltisatopicofdisagreementamongchildpsychologists.

D.ltisrelatedtobiologicaldevelopmentsinthechild'sbrain.

第17题

Whydoestheauthormentionwords,gestures,andpicturesinparagraph2?

A.Tolistthingsthatareusedinexperimentswithchildren

B.Ibgiveexamplesofsymbolsthatchildrencanunderstand

C.Ibcomparedifferentwaysofillustratingachild'sexperience

D.Toillustratetheconceptofconservationofquantity

第18题

Thewordpeakinparagraph2isclosestinmeaningto

A.largevocabulary

B.difficultperiod

C.highpoint

D.suddenreversal

第19题

Thewordappreciateinparagraph3isclosestinmeaningto

A.admire

B.understand

C.dismiss

□.create

第20题

Accordingtothepassage,achildwhoiscapableofconcreteoperationscan

A.performtasksthatmayconfuseanadult

B.installanextracardonacomputer

C.maketworowsofcoinslookthesame

D.reasonsystematicallyaboutquantityandspace

第21题

Thewordhallmarkinparagraph4isclosestinmeaningto

A.characteristic

B.problem

C.disadvantage

□.experiment

第22题

Whichsentencebelowbestexpressestheessentialinformationinthehighlightedsentencein

paragraph4?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessential

information.

A.Beforetheageoffive,childrenthinkthelongerlinehasmorecoinsbecausetheyare

incapableofunderstandingconservation.

B.Five-year-oldchildrendonotunderstandthevalueofmoney,sotheydonotcareifonelineof

coinsislongerthananother.

C.Becauseofthefive-sevenshift,childrencanunderstandwhythelongerrowofcoinsisa

betterexampleofconservation.

D.Eveniftworowsofcoinsaredifferentinlength,veryyoungchildrenwillsaythatbothrows

havethesamenumberofcoins.

第23题

Inparagraph5,theauthordescribesanexperimentinwhichwaterispouredintovariousglasses

inorderto

A.showhowchildrenapproachdifficultproblems

B.recommendanexperimentthatcanbedoneathome

C.giveavariationonaclassicexperimentbyPiaget

□.suggestanactivityforparentsandchildren

第24题

Whatcanbeinferredaboutchildrenwhoeasilysolvethewatertaskdescribedinparagraph5?

A.Theyhavealreadyexperiencedthefive-sevenshift.

B.Theyweretaughtabouttheconceptofconservation.

C.Theyhadtimetopracticethetaskbeforetheexperiment.

D.Theyaremoreintelligentthanothersofthesameage.

第25题

Lookatthefoursquares,AzB,C,andD,whichindicatewherethefollowingsentencecouldbe

addedtothepassage.Wherewouldthesentencebestfit?

Forinstance,whensandispouredbackandforthbetweencontainersofdifferentsizesand

shapes,thequantityofsanddoesnotchange.

Piagetdiscoveredthemostwidelyknownhallmarkofthefive-sevenshift,anunderstandingof

conservation,theideathatsomepropertiesstaythesamedespitechangesinappearance.AIn

oneofPiaget'sclassicexperimentsontheconservationofquantity,theexperimentershows

childrenofdifferentagestwostraightrowsofcoins,eachwithsixcoinspressedclosetogether,

besideeachotheronatable.BTheexperimenteraskseachchildsubjectwhetherbothrows

havethesamenumberofcoinsorwhetheronerowhasmore.Thentheexperimenterspreads

outthecoinsofonerowtomakethelinelooklonger.CThechildmustnowsaywhetheronerow

hasmorecoins.Childrenyoungerthanfiveyearsoldcannotunderstandconservation,sothey

invariablysaythatthespread-outrowhasmorecoinsthantheotherrow.D

第26题

Selecttheappropriatesentencesfromtheanswerchoicesandmatchthemtotheperiodbefore

orafterthefive-sevenshift.TWOoftheanswerchoiceswillNOTbeused.Thisquestionisworth

3points.

BeforetheFive-SevenShift

AftertheFive-SevenShift

AnswerChoices

A.Thechild'sbrainwaveshaverhythmssimilartothoseofadults.

B.Thechild'scognitivedevelopmentcannotbemeasuredscientifically.

C.Thechildlearnsinsimplewaysandcanfocusononlyonequalityatatime.

D.Thechildknowsthatthequantitystaysthesamewhenobjectsarerearranged.

E.Thechildcannotdistinguishbetweenrightandwrong.

F.Thechildcanquicklysolveproblemsinvolvingconservation.

G.Thechildisnotabletounderstandtheconservationofquantity.

上一题下一题

（27~39/共52题）阅读理解

SOILQUALITY

1Soilisarenewableresource,butonlyonaverylongtimescale,asittakeshundredsor

thousandsofyearsforthenaturalprocessesoferosion,organicdecay,andaccumulationto

createsoils.Soilqualityandthepotentialtoproducecropscanvaryenormouslyfromregionto

regionandamongvarioussoiltypes.

2Oneimportantfactoraffectingtheproductivityofsoilsovertimeisagriculture.Top-quality

landsarebroughtintoproductionearlierbecauseoftheirhigherpotentialtoproducefood.As

moreandmorelandhasbeenbroughtunderagriculturalproduction,theaveragequalityofland

hasdecreased,reducingpotentialproductivityperhectare.Cropsdepletesoilfertilityby

consumingnutrients,andthiseventuallyreducescropyields.Poormanagementpracticesleadto

soilcompactionandsoilpollutionaswellaslossofsoilcover.Withoutpropermanagementand

theconstantadditionofnutrientsandenergyintheformoffertilizersandirrigation,crop

productionfailsovertime.

3Withinthescientificcommunity,thereislittledoubtthatsoilqualityisdiminishinginmany

areasaroundtheworld.Scientistshavefoundthatthequalityofonequarteroftheworld'ssoils

hasexperiencedsomeloss,andthepaceofdegradationhasacceleratedoverthepast50years.

Thelossofsoilfertilityhascausedaslowinginthegrowthofagriculturalproductivity.Annual

cropstendtodegradesoilsmorethanperennialcrops,andcommonpropertylandsgenerally

suffermoredegradationthanprivatelands.

4Today,irrigatedcroplandproducesaboutone-thirdoftheworld'sfood.Approximately18

percentoftheworld'scroplandisirrigated,andscientistsprojectthisamounttodoubleinthe

nextdecade.Irrigationcanincreasecropyieldsperhectaretotwoorthreetimestheyieldsof

landwateredonlybyrain.However;therearealsosomeharmfulsideeffects.Besidesincreasing

cropproductivityintheshortrun,irrigationcanleadtosharpdropsincropproductivityinthe

longrunbycausingexcessivesaltbuildupandrisingwatertables.

5Oneofthemostcriticalsoilqualityproblemsrelatedtoirrigationistheincreasein

concentrationofdissolvedsalts.Thisprocess,salinization,affectsanestimatedone-fourthofthe

world'sirrigatedcropland.Insomeplaces,irrigationwatercontainsasmuchas3.5tonsofsalt

per1,000cubicmeters.Asthewaterflowsoverandthroughtheground,itdissolvessalts,

increasingthesalinityofthewater.Sincesomecropsrequire6,000to10,000cubicmetersof

waterperhectare,landcanreceivetensoftonsofsaltperhectare.Asthewaterevaporates,high

concentrationsofsaltssuchassodiumchlorideareleftbehindinthetopsoil.Saltbuildupcan

stuntcropgrowth,decreaseyields,killcropplants,andeventuallymakethelandunproductive.

6Aproblemthatoftenaccompaniessalinizationindryregionsiswaterlogging,whichoften

occurswhenfarmersapplyheavyamountsofirrigationwaterinanattempttopreventsaltsfrom

accumulating.However,unlessthewaterdrainsproperly,itcollectsundergroundandgradually

raisesthewatertableclosertothesurface,therebybringingsaltstothesurfaceand

concentratingthem.Saltwaterthenenvelopsthefragilerootsystemsofplants,killingtheplants

andconvertingfertilefieldstowetdeserts.ThisisaparticularlyseriousprobleminCalifornia's

heavilyirrigatedSanJoaquinValley,wheresoilscontainaclaylayerthatpreventswaterfrom

flowingthroughtheground.Worldwide,atleastone-tenthofallirrigatedlandissubjectto

waterlogging.

7Anotherserioussoilproblemiserosion,thelossofsoilsfromwaterandwindaction.Soil

erosionoccursonagriculturallandwithoutvegetativecoverforprotectionorbecauseofpoor

agriculturalmanagement.Scientistsestimatethattopsoiloncultivatedlandisbeinglost16to

300timesfasterthanitisbeingreplaced.Inmanypartsoftheworld,ashiftawayfrom

traditionalagriculturalpracticesisplacinggreaterpressureonthesoil,whichinturniscausingan

increaseinsoilerosionrates.StudiesintheUnitedStatessuggestthatthelossofjust2.5

centimetersoftopsoilreducescornandwheatyieldsby6percent.

第27题

Accordingtothepassage,allofthefollowingcontributetosoildegradationEXCEPT

A.pooragriculturalmanagement

B.rotationofannualcrops

C.accumulationofsalts

D.lackofwaterdrainage

第28题

Theworddepleteinparagraph2isclosestinmeaningto

A.reduce

B.attract

C.prepare

0.create

第29题

Whichsentencebelowbestexpressestheessentialinformationinthehighlightedsentencein

paragraph3?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessential

information.

A.Thescientificstudyofsoilsisimprovingsoilqualityinmanyregionsworldwide.

B.Fewpeoplewoulddisagreethatsoilqualityisasdiminishedasscientistssayitis.

C.Thenumberofscientistswhospecializeinthestudyofsoilshasbeendecreasing.

D.Mostscientistsagreethatsoildegradationisoccurringinmanypartsoftheworld.

第30题

Whatcanbeinferredfromparagraph3aboutannualcropsoncommonpropertylands?

A.Theyhavebeenpartofagricultureforonlythepastfiftyyears.

B.Theyarenotconsideredtobesignificantcausesofsoildegradation.

C.Theyproducemoreincomethanperennialcropsonprivatelandsdo.

D.Theymaydecreasesoilfertilityandagriculturalproductivity.

第31题

Accordingtothepassage,whichofthefollowingisaseriousconsequenceofirrigation?

A.Lossoffreshwaterfordrinking

B.Decreaseinthelevelofrivers

C.Excessivebuildupofsaltsinthesoil

0.Increaseintherateofsoilerosion

第32题

Inwhatwayissalinizationaseriousproblemforagriculture?

A.Soilswithhighsaltconcentrationsaredestructivetocropplants.

B.Salinizationcanleadtosoilcompactionortolossofsoilcover.

C.Excessiveamountsofwaterarerequiredtopreventsalinization.

□.Addingsalttofertilizerraisestheoperatingcostsofagriculture.

第33题

Thewordstuntinparagraph5isclosestinmeaningto

A.speed

B.hide

C.cause

D.limit

第34题

Thetermwaterlogginginparagraph6meansthat

A.logsarefloatinginwater

B.waterisnotavailable

C.thesoilholdstoomuchwater

D.saltsareremovedfromwater

第35题

Howarewaterloggingandsalinizationrelated?

A.Salinizationoccursonlywherewaterloggingisaproblem.

B.Waterloggingraisesandconcentratessaltsnearthesurface.

C.Farmersaddsaltstoirrigationwaterasawaytofertilizesoil.

D.Bothwaterloggingandsalinizationcontributetosoilerosion.

第36题

Thewordenvelopsinparagraph6isclosestinmeaningto

A.darkens

B.surrounds

C.exits

D.purifies

第37题

Whydoestheauthormentioncornandwheatyieldsinparagraph7?

A.Toillustratetheeffectofasmallamountoferosion

B.Ibexplainwhyerosionaffectsonlycertaincrops

C.Todescribetheresultofashiftfromtraditionalpractices

D.Toshowhowpoormanagementinfluencescropyields

第38题

Lookatthefoursquares,A,B,C,andD,whichindicatewherethefollowingsentencecouldbe

addedtothepassage.Wherewouldthesentencebestfit?

Unlesstheyareflushedordrainedfromthesoil,theirbuildupmaycauseanumberofserious

problems.

Oneofthemostcriticalsoilqualityproblemsrelatedtoirrigationistheincreaseinconcentration

ofdissolvedsalts.Thisprocess,salinization,affectsanestimatedone-fourthoftheworld's

irrigatedcropland.Insomeplaces,irrigationwatercontainsasmuchas3.5tonsofsaltper1,000

cubicmeters.AAsthewaterflowsoverandthroughtheground,itdissolvessalts,increasingthe

salinityofthewater.BSincesomecropsrequire6,000to10,000cubicmetersofwaterper

hectare,landcanreceivetensoftonsofsaltperhectare.CAsthewaterevaporates,high

co