Antarcticahasactuallybecomeakindofspacestationauniqueobservationpostfordetectingimportantchangesintheworld'senvironment.Remotefrommajorsourcesofpollutionandthecomplexgeologicalandecologicalsystemsthatprevailelsewhere,Antarcticamakespossiblescientificmeasurementsthatareoftensharperandeasiertointerpretthanthosemadeinotherpartsoftheworld.
GrowingnumbersofscientiststhereforeseeAntarcticaasadistant-early-warningsensor,wherepotentiallydangerousglobaltrendsmaybespottedbeforetheyshowuptothenorth.Onepromisingfieldofinvestigationisglaciology.ScholarsfromtheUnitedStates,Switzerland,andFrancearepursuingsevenseparatebutrelatedprojectsthatreflecttheirconcernforthehealthoftheWestAntarcticIceSheetaconcerntheybelievetheworldatlargeshouldshare.
TheTransantarcticMountain,someofthemmorethan14,000feethigh,dividethecontinentintotwoverydifferentregions.Thepartofthecontinenttothe"east"ofthemountainsisahighplateaucoveredbyanicesheetnearlytwomilesthick."West"ofthemountain,thehalfofthecontinentsouthoftheAmericasisalsocoveredbyanicesheet,buttheretheicerestsonrockthatismostlywellbelowsealevel.IftheWestAntarcticIceSheetdisappeared,thewesternpartofthecontinentwouldbereducedtoasparseclusterofisland.
Whileiceandsnowareobviouslycentraltomanyenvironmentalexperiments,othersfocusonthemysterious"dryvalley"ofAntarctica,valleysthatcontainlittleiceorsnoweveninthedepthsofwinter.SlashedthroughthemountainsofsouthernVictoriaLand,thesevalleysonceheldenormousglaciersthatdescended9,000feetfromthepolarplateautotheRossSea.Nowtheglaciersaregone,perhapsacasualtyoftheglobalwarmingtrendduringthe10,000yearssincetheiceage.Eventhesnowthatfallsinthedryvalleysisblastedoutbyviciouswindsthatroarsdownfromthepolarplateautothesea.Leftbarearespectaculargorges,rippledfieldsofsanddunes,clustersofboulderssculpturedintofantasticshapesby100-mile-an-hourwinds,andanauraofextraterrestrialdesolation.
Despitetheunearthlyaspectofthedryvalleys,somescientistsbelievetheymaycarryamessageofhopeoftheverdantpartsoftheearth.Somescientistsbelievethatinsomecasesthedryvalleysmaysoakuppollutantsfasterthanpollutantsenterthem.
1.Whatisthebesttitleforthispassage?
[A]AntarcticaandenvironmentalProblems.
[B]Antarctica:Earth'sEarly-Warningstation.
[C]Antarctica:aUniqueObservationPost.
[D]Antarctica:aMysteriousPlace.
2.WhatwouldtheresultbeiftheWestAntarcticIceSheetdisappeared?
[A]Thewesternpartofthecontinentwouldbedisappeared.
[B]Thewesternpartofthecontinentwouldbereduced.
[C]ThewesternpartofthecontinentwouldbecomescatteredIslands.
[D]ThewesternpartofthecontinentwouldbereducedtoaclusterofIslands.
3.WhyaretheDryValleysleftbare?
[A]Viciouswindblaststhesnowaway.
[C]Becauseoftheglobalwarmingtrendandfiercewind.
4.Whichofthefollowingistrue?
[A]The"DryValleys"havenothingleftinside.
[B]The"DryValleys"neverheldglaciers.
[C]The"DryValleys"maycarryamessageofhopefortheverdant.
[D]The"DryValleys"areuselesstoscientists.
1.A南极洲和环境问题。B.南极洲：地球最早的报警战。C.南极洲：独一无二的观察哨。D.南极洲：神秘的地方。三项都是总内容众的组成部分。
2.D大陆西部成为一群岛屿。第三段“横断南极的山脉，有的高达一万四千多英尺，把这大陆分成情况各异的两个地区。山脉以东的大陆部分是由差不多两英里厚的冰层覆盖的高原;山脉以西，即美洲以南的半个大陆也为冰层所覆盖。可是，这里冰层覆盖在大大低于海平面的岩石。如果西南极洲冰层消失，那这大陆西部将成为稀疏的岛群。”A.大陆西部将小时。B.大陆西部缩小。D.大陆西部将成为分散的岛屿。
3.C因为地球变暖和狂风劲吹。在第四段：“……这些干谷甚至在寒冬季节也很少有冰雪。它们插在南维多利亚陆地的山脉中，一度曾有从极地高原到罗斯海的深度为9000英尺的冰河。现在冰河已不存在，很可能是冰期之后一万年间地球变暖的结果。即使落入干谷的雪也被从极地高原咆哮入海的邪恶狂风吹散了。留下来的是裸露的壮观的峡谷，沙丘起伏的原野，被时速一百英里的大风雕刻成奇形怪状的大砾石，形成与世隔绝的荒凉景象。”A.邪恶的狂风吹走了雪。B.它很少下雪。D.沙丘。这三项只是干谷现象的一部分。
4.C他们可能为地球上绿色地区带来了希望的信息。答案是第五段第一句“尽管干谷具有神秘的一面，科学家却相信他们可能为地球上葱绿的地方带来了希望的信息。”A.干谷内什么都没有留下。B.干谷内从没有冰河。D.按照科学家的看法，干谷毫无用处。
