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1、【王鑫托福阅读】托福TPO全集之TPO31-3TPO31TP031-3SavannaFormation1.Theword"prolonged"inthepassageisclosestinmeaningtoAPredictableBDestructiveCLengthyDUnproductive2.Inparagraph2,thesilthormentionssavannasinCentralAmerica,Brazi1,andtheislandofTrinidadinordertoAArguethatthosesavannasaresimilartothose
2、inSouthAmericaandCubaBPointoutexceptionstothepatternofsavarmaformationinareaswithdroughtstressCProvidesadditionalexamplesofsavarrnasinareaswithfive toeight-monthwetseasonsDIndicateareaswheresavannasarebeinggraduallyreplacedbyrainforests3・Accordingtoparagraph3,rainforestsandsavannasdi
3、fferinthatAThesoilsinrainforestscontainfewermineralsthansavannasoilsdoBSavannasaffectsoilconditionsmorethanrainforestsdoCUnlikerainforests,savannasprefersandy,well-drainedsoilstosoiIsthatareverywetDUniikerainforests,savannasmaydevelopunderbothverydryandverywetsoi1conditionsLocatedint
4、ropicalareasatlowaltitudes,savanrmsarestableecosystems,somewetandsomedryconsistingofvastgrasslandswithscatteredtreesandshrubs.Theyoccuronawiderangeofsoiltypesandinextremesofclimate・Thereisnosimpleorsinglefactorthatdeterminesifagivensitewillbeasavann弘butsomefactorsseemtoplayimportantr
5、olesintheirformation.SavannastypicallyexperieneearatherproIongeddryseason.Onetheorybehindsavannaformationisthatwetforestspeciesareunabletowithstandthedryseason,andthussavanna,ratherthanrainforest,isfavoredonthesite.Savannasexperienceanarmualrainfal1ofbetween1,000and2,000millimeters,m
6、ostofitfallinginafive-toeight-monthwetseason.Thoughplentyofrainmayfallonasavannaduringtheyear,foratleastpartoftheyearlittledoes,creatingthedroughtstressultimatelyfavoringgrasses・Suchconditionsprevai1throughoutmuchofnorthernSouthAmericaandCuba,butmanyCentra.1Americansavannasaswel1asco
7、astalareasofBrazi1andtheislandofTrinidaddonotfitthispattern.Intheseareas,rainfallpermonthexceedsthatintheabovedefinilion,sootherfactorsmustcontributetosavannaformation.Tnmanycharacteristics,savannasoilsaresimilartothoseofsomerainforests,thoughmoreextreme.Forexample,savannasoils,likem
8、anyrainfores
