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TPOSavannaLocatedintropicalareasatlowaltitudes,savannasarestableecosystems,somewetandsomedryconsistingofvastgrasslandswithscatteredtreesorshrubs.Theyoccuronawiderangeofsoiltypesandinextremesofclimate.Thereisnosimpleorsinglefactorthatdeterminesifagivensitewillbeasavanna,butsomefactorsseemtoplayimportantrolesintheirformation.>SavannastypicallyexperienceaTPOSavannaLocatedintropicalareasatlowaltitudes,savannasarestableecosystems,somewetandsomedryconsistingofvastgrasslandswithscatteredtreesorshrubs.Theyoccuronawiderangeofsoiltypesandinextremesofclimate.Thereisnosimpleorsinglefactorthatdeterminesifagivensitewillbeasavanna,butsomefactorsseemtoplayimportantrolesintheirformation.>Savannastypicallyexperiencea[楊雪瀅1]:正確答案：C文中prolonged，詞根long，長度。Prolonged為延長的。選項中C，length本來是長behindsavannaformationisthatforestspeciesareunabletowithstandthedryseason,andthussavanna,ratherthanrainforest,isfavoredonthesite.Savannasexperienceanannualrainfallof的意思，lengthy變?yōu)樾稳軶2Inparagraph2,theauthorsavannasinCentralAmerica,Brazil,andtheislandofTrinidadinorderto:between1,000and2,000mostofitfallinginafive‐towetseason.Thoughplentyofrain格式，符合原詞詞義解析savannasinCentralAmerica,Brazil,andtheofTrinidad作為關(guān)鍵詞定位到也就是說centralamercia，brazil這些地方和前面介紹的arguethatthesesavannasaresimilarthoseinSouthAmericaandCubapointoutexceptionstothepatternofsavannaformationinareaswithdroughtprovideadditionalexamplesofsavannasinareaswithfive‐toeight‐monthwetindicateareaswheresavannasarebeinggraduallyreplacedbyrainforestsfallonasavannaduringtheyear,forleastpartoftheyearlittledoes,creatingthedroughtstressultimatelyfavoringgrasses.SuchconditionsprevailthroughoutmuchofnorthernSouthAmericaandCuba,butmanyCentralAmericansavannasaswellascoastalareasofBrazilandtheislandofTrinidaddonotfitthispattern.Intheseareas,rainfallpermonthexceedsthatintheabovedefinition,sootherfactorsmustcontributetosavannaformation.Paragraph2ismarkedwithan就給給了examples最后一句mayseem….Eithertoowetortoodryforforests”所以選Q3Accordingtoparagraph3,rainforestssavannasdifferin>Inmanycharacteristics,savannaaresimilartothoseofsomerainthesoilsinrainforestscontainmineralsthansavannasoilssavannasaffectsoilconditionsmorethanrainforestsdothoughmoreextreme.Forsavannasoils,likemanyrainforestsoils,aretypicallyoxisols(dominatedbycertainoxideminerals)andultisols(soilsQ1Theword"prolonged"inthepassageclosestinmeaningprolongeddryseason.Oneunlikerainforests,savannaspreferwell‐drainedsoilstosoilsthatareveryunlikerainforests,savannasmaydevelopunderbothverydryandverywetsoilParagraph3ismarkedwithunlikerainforests,savannaspreferwell‐drainedsoilstosoilsthatareveryunlikerainforests,savannasmaydevelopunderbothverydryandverywetsoilParagraph3ismarkedwithancontainingnocalciumcarbonate),withhighacidityandnotablylowconcentrationsofsuchmineralsasphosphorus,calcium,magnesium,andpotassium,whilealuminumlevelsarehigh.Somesavannasoccuronwet,waterloggedsoils;othersondry,sandy,Notablynotice發(fā)展而來，外也可通過and的并列格式來推斷extremesoilconditions,eithertooortoodryforforests,aresatisfactoryforsavannas.Moremoderateconditionssupportmoistforests.Q5Accordingtoparagraph3,alloffollowingaretrueofsavannasoils這一forexample后面的內(nèi)容，A直接和紅色標(biāo)注部分矛盾，因此是要選except的選項TheyhavehighconcentrationsTheycontainhighlevelsofaluminum.Theyareveryacidic.Theycontainlargeamountsofcertainoxideminerals.Paragraph3ismarkedwithanQ6Accordingtoparagraph4,whichoffollowingistrueofwaterlogged>Waterloggedsoilsoccurinareasareflatorhavepoordrainage.TheirupperlayersareusuallysandyTheycannotsupportsavannas.Theycontainlittleoxygen.Theyarepronetotheleachingofnutrientsandminerals.soilsusuallycontainlargeamountsclayandeasilybecomewater‐saturated.Arecannotpenetratebetweenthesoilparticles,makingthesoiloxygen‐poor.Bycontrast,drysoilsaresandyandporous,theircoarsetexturespermittingwatertodrainrapidly.Sandysoilsarepronetoleachingofnutrientsandmineralsandsotendtobenutritionallypoor.Thoughmostsavannasarefoundonsiteswihpoorsoils(becauseofeithermoistureconditionsornutrientlevelsofboth),poorsoilscananddosupportlushrainParagraph4ismarkedwithan poorsoilsalonemaynotbeenoughexplainwhyanareabecomesarainforestvegetationcanlowerthequalityofdroughtstressisthesinglemostimportantfactorinsavannaformationmineralsaremoreimportantthanmoistureforthegrowthoftreesQ7Thefactthat"poorsoilscanandsupportlushrainforest"suggests解析：A對于“bycontrast…“那一句，sandysoil和就是很濕的那種。C對于那個makingthesoiloxygen-poor。D對應(yīng)“Sandysoilsareproneto而不是選項中說的waterloggedsoils的特征。批注[楊雪瀅7]:正確答案A的savannas都發(fā)生在poorsoils之上poorsoils足是轉(zhuǎn)折，說明poorsoils不是唯一決定了savannas的因素，還有別Q4Theword"notably"inthepassagewell‐drainedsoils.Thismayclosestinmeaningcontradictory,butitonlymeans>Mostsavannasprobablymildfiresfrequentlyandmajorburnseverytwoyearsorso.Manysavannaanddry‐forestplantspeciesarecalledexpressestheessentialinformationinhighlightedsentenceinthepassage?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.pyrophytes,meaningthey>Mostsavannasprobablymildfiresfrequentlyandmajorburnseverytwoyearsorso.Manysavannaanddry‐forestplantspeciesarecalledexpressestheessentialinformationinhighlightedsentenceinthepassage?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.pyrophytes,meaningtheyareadapted[楊雪瀅8]:正確答案解析：原句主干是說RainforestspeciesseemunabletotofirescreatedbyAncientcharcoalremainssuggestthat,priortothearrivalofhumans,firesoccurredfrequentlyinrainforests.AncientcharcoalremainsinAmazonforestssuggestthatrainforestspeciesadaptedtothearealongbeforethearrivalofhumans.Rainforestspeciesappearunabletoadapttofrequentfires,butevidencefromthepastsuggeststhatrainforestssometimesdoburn.variouswaystowithstandburning.Frequentfireisafactortowhichfire是造成熱帶雨林不能形rainforestspeciesseemunableto燃燒。所以D是意思最的?？筛鶕?jù)轉(zhuǎn)折關(guān)系來判斷althoughancientcharcoalremainsAmazonforestsoilsdatingpriortothearrivalofhumanssuggestthatmoistforestsalsooccasionallyburn.ExperimentssuggestthatiffiredidoccurinsavannasintheAmericas,speciescompositionwouldchangesignificantly.Whenburningoccurs,itpreventscompetitionamongplantspeciesfromprogressingtothepointwheresomespeciesexcludeothers,reducingtheoveralldiversityoftheecosystem.ButinexperimentalareasQ9Theword"markedly"inthepassageclosestinmeaning[楊雪瀅9]:正確答案specieseventuallycometooutcompetingallothers.Evidencefromotherstudiessuggeststhatexclusionoffireresultsinmarkedlydecreasedplant‐speciesrichness,oftenwithanincreaseintreedensity.Thereisgenerallylittledoubtthatfireisamark意為標(biāo)注，跟選中B的notice意思相近，所以選BQ10Paragraph5supportswhichoffollowingstatementsregardingtheimportanceoffiresinmaintainingsavannas?FirespreventthegrowthofFireseliminatesomespeciesandthusreducetheoveralldiversityoftheFiresthatoccuronceeverytwoyearsareunlikelytohelpmaintainsavannas.FirespreventsomespeciesfromeliminatingotherspecieswithwhichtheysignificantfactorinmaintainingcertainlyinmostParagraph5ismarkedwithanQ11Theword"subsequent"inthepassageclosestinmeaning>Oncertainsites,particularlyinAmerica,savannaformationA.expandedinrelatedtofrequentcuttingand[楊雪瀅10]:正確答案D解析：對應(yīng)部分從butinexperimentalareasprotected就很少有perennialgrassspecies可以outcompeting其密度則會更大。對應(yīng)了D的批注[楊雪瀅11]:正確答案C解析：subsequence是后果的然后的意思。因此選擇CQ8Whichofthesentencesbelowofmoistforestsforpastureland.inpasturelandandsubsequentovergrazinghaveresultedinanexpansionofsavanna.Thethinupperlayerofhumus(decayedorganicofmoistforestsforpastureland.inpasturelandandsubsequentovergrazinghaveresultedinanexpansionofsavanna.Thethinupperlayerofhumus(decayedorganicmatter)isdestroyedbycuttingandburning.HumusisnecessaryforQ12Accordingtoparagraph6,humanaffectssoilsinallofthefollowingways[楊雪瀅12]:正確答案A解析：humanactivity包括了就是后果。先說humusDecompositionofleavesoccurstooforsurfacerootstoobtainnutrients.Nutrientsarenotrecycled.HumusisCertainsoilsbecomeunabletosupportvegetationotherthansavannavegetation.decompositionofleavesbybacteriafungiandforrecyclingbysurfaceroots.Oncethehumuslayerdisappears,nutrientscannotberecycledandleachfromthesoil,convertingsoilfromfertiletoinfertileandmakingitsuitableonlyfordestroyed，對應(yīng)C，然后Paragraph6ismarkedwithansavannavegetation.Forestsonsandysoilaremostsusceptibletopermanentalteration.對于decomposition是非常必要的，而humanactivitydestroy了humus，所以減慢了decompositionA矛盾。后面說nutrientscannot被recycledBconverting那一句對應(yīng)了Evidencefromotherstudiessuggeststhatexclusionoffireresultsinmarkedlydecreasedplant‐speciesrichness,oftenwherethefollowingsentencecouldbetothe[楊雪瀅13]:正確答案C頭是inaddition，證明是對前應(yīng)該是savannas形成的原因cuttingburning，這些都是humanactivity。所以選withanincreaseintreedensity.■Thereisgenerallylittledoubtthatfireisasignificantfactorinmaintainingsavanna,certainlyinmostregions.■Oncertainsites,particularlyinSouthAmerica,savannaformationseemsrelatedtofrequentcuttingandburningofmoistforestsforpastureland.■IncreaseinpasturelandandsubsequentovergrazinghaveresultedinanexpansionofInaddition,humanshavecontributedtoconditionsfavoringtheformationofWherewouldthesentencebestfit?ClickonsquaretoaddthesentencetotheQ14Directions:Anintroductorysentenceforbriefsummaryofth