托福阅读tpo12解析及答案下载三

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1、托福阅读TPO12解析及答案下载三　　托福阅读TPO12解析及答案下载三!为大家顺利备战托福阅读，小编为大家整理了托福阅读考试TPO试题的相关解析与答案，其中的解析非常详尽，同学们可以进行下载参考使用。　　TPO12-1-3原文：WaterintheDesert　　Rainfallisnotcompletelyabsentindesertareas,butitishighlyvariable.Anannualrainfalloffourinchesisoftenusedtodefinethelimitsofades

2、ert.Theimpactofrainfalluponthesurfacewaterandgroundwaterresourcesofthedesertisgreatlyinfluencedbylandforms.Flatsanddepressionswherewatercancollectarecommonfeatures,buttheymakeuponlyasmallpartofthelandscape.　　Aridlands,surprisingly,containsomeoftheworld’slarges

3、triversystems,suchastheMurray-DarlinginAustralia,theRioGrandeinNorthAmerica,theIndusinAsia,andtheNileinAfrica.Theseriversandriversystemsareknownas"exogenous"becausetheirsourceslieoutsidethearidzone.Theyarevitalforsustaininglifeinsomeofthedriestpartsoftheworld.

4、Forcenturies,theannualfloodsoftheNile,Tigris,andEuphrates,forexample,havebroughtfertilesiltsandwatertotheinhabitantsoftheirlowervalleys.Today,riverdischargesareincreasinglycontrolledbyhumanintervention,creatinganeedforinternationalriver-basinagreements.Thefill

5、ingoftheAtaturkandotherdamsinTurkeyhasdrasticallyreducedflowsintheEuphrates,withpotentiallyseriousconsequencesforSyriaandIraq.　　Theflowofexogenousriversvarieswiththeseason.Thedesertsectionsoflongriversrespondseveralmonthsafterrainhasfallenoutsidethedesert,soth

6、atpeakflowsmaybeinthedryseason.Thisisusefulforirrigation,butthehightemperatures,lowhumidities,anddifferentdaylengthsofthedryseason,comparedtothenormalgrowingseason,canpresentdifficultieswithsomecrops.　　Regularlyflowingriversandstreamsthatoriginatewithinaridlan

7、dsareknownas"endogenous."Thesearegenerallyfedbygroundwatersprings,andmanyissuefromlimestonemassifs,suchastheAtlasMountainsinMorocco.Basalticrocksalsosupportsprings,notablyattheJabalAl-ArabontheJordan-Syriaborder.Endogenousriversoftendonotreachtheseabutdrainint

8、oinlandbasins,wherethewaterevaporatesorislostintheground.Mostdesertstreambedsarenormallydry,buttheyoccasionallyreceivelargeflowsofwaterandsediment.　　Desertscontainlargeamountsofgro