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阅读原文：?Groundwateristhewordusedtodescribewaterthatsaturatestheground,fillingalltheavailablespaces.Byfarthemostabundanttypeofgroundwaterismeteoricwater;thisisthegroundwaterthatcirculatesaspartofthewatercycle.Ordinarymeteoricwateriswaterthathassoakedintothegroundfromthesurface,fromprecipitation(rainandsnow)andfromlakesandstreams.Thereitremains,sometimesforlongperiods,beforeemergingatthesurfaceagain.Atfirstthoughtitseemsincrediblethattherecanbeenoughspaceinthesolidgroundunderfoottoholdallthiswater.地下水是指渗入到地下并将所有岩石孔隙填满的水。到现在为止，大气水是最丰富的地下水资源，是地下水在水循环中的一个环节。普通的大气水会从地表、降水以及湖泊河流侵入到地下。在再次冒出地表之前，这些地下水有时会长时间留在地下。最初让人觉得难以置信的是，在我们脚下“坚实的”土地中竟然有足够的空间能储存这么些水。Thenecessaryspaceisthere,however,inmanyforms.Thecommonestspacesarethoseamongtheparticles—sandgrainsandtinypebbles—ofloose,unconsolidatedsandandgravel.Bedsofthismaterial,outofsightbeneaththesoil,arecommon.Theyarefoundwhereverfastriverscarryingloadsofcoarsesedimentonceflowed.Forexample,asthegreaticesheetsthatcoveredNorthAmericaduringthelasticeagesteadilymeltedaway,hugevolumesofwaterflowedfromthem.Thewaterwasalwaysladenwithpebbles,gravel,andsand,knownasglacialoutwash,thatwasdepositedastheflowsloweddown.然而，地下水所需的储存空间多种多样。松散的砂子和砾石间有许多颗粒，如沙粒和小石子，它们之间的孔隙是最常见的储存地下水的空间。由这些颗粒组成的水床非常普遍，通常位于看不见的土壤下方，在携带粗糙沉淀物的湍急的河流曾流过的地方都能找到它们的踪迹。比如，冰河时代覆盖北美的巨大冰层逐渐融化，大量水从那儿流出。水里总会携带些石子、砾石和沙石，这些颗粒会随着水流的减速而沉淀，这就是所谓冰河期的冰水沉积。Thesamethinghappenstothisday,thoughonasmallerscale,whereverasediment-ladenriverorstreamemergesfromamountainvalleyontorelativelyflatland,droppingitsloadasthecurrentslows:thewaterusuallyspreadsoutfanwise,depositingthesedimentintheformofasmooth,fan-shapedslope.Sedimentsarealsodroppedwhereariverslowsonenteringalakeorthesea,thedepositedsedimentsareonalakefloorortheseaflooratfirst,butwillbelocatedinlandatsomefuturedate,whenthesealevelfallsorthelandrises;suchbedsaresometimesthousandsofmetersthick.现代也有冰水沉积，尽管规模相对较小。凡是有携带沙石的河流或者溪流从山谷流至相对平坦的地面时，砂石就随着水流速度的减慢逐渐沉淀；水流通常呈扇形扩散，它们所携带的沙石也会沉淀为光滑的扇形斜面。当河流汇入湖泊和海洋的时候也会有沉淀，这些沉淀最初在湖底或海底，但将来海平面下降或者陆地崛起时，它们就会分布于内陆，通常厚达几千米。Inlowlandcountryalmostanyspotonthegroundmayoverliewhatwasoncethebedofariverthathassincebecomeburiedbysoil;iftheyarenowbelowthewater’suppersurface(thewatertable),thegravelsandsandsoftheformerriverbed,anditssandbars,willbesaturatedwithgroundwater.低地区域上的任何位置可能就是曾经的河床，后续被土壤覆盖而变成现在的样子。如果那些过去的河床和沙洲现在位于地下水位之下，一定会有大量的地下水浸在它们的沙子和砾石之间。Somuchforunconsolidatedsediments.Consolidated(orcemented)sediments,too,containmillionsofminutewater-holdingpores.Thisisbecausethegapsamongtheoriginalgrainsareoftennottotallypluggedwithcementingchemicals;also,partsoftheoriginalgrainsmaybecomedissolvedbypercolatinggroundwater,eitherwhileconsolidationistakingplaceoratanytimeafterwards.Theresultisthatsandstone,forexample,canbeasporousastheloosesandfromwhichitwasformed.以上说的都是松散的沉积物，那些坚固的沉积物，也拥有以数万计的毛细孔来容纳水。因为最初颗粒间的缝隙通常并未完全被黏固的化学物质塞满，而且部分颗粒很可能在固化时或固化后被渗入的地下水溶解；结果这些砂岩最终变得和形成它的散沙一样多孔。Thusaproportionofthetotalvolumeofanysediment,looseorcemented,consistsofemptyspace.Mostcrystallinerocksaremuchmoresolid;acommonexceptionisbasalt,aformofsolidifiedvolcaniclava,whichissometimesfulloftinybubblesthatmakeitveryporous.因此，不管沉积物是疏松还是坚固，它们中一定有空间。大部分结晶体岩石都非常坚硬，但也有例外，最常见的就是玄武岩，它是一种固化的火山熔岩，经常充满了微小气泡，从而变得十分多孔。Theproportionofemptyspaceinarockisknownasitsporosity.Butnotethatporosityisnotthesameaspermeability,whichmeasurestheeasewithwhichwatercanflowthroughamaterial;thisdependsonthesizesoftheindividualcavitiesandthecreviceslinkingthem.岩石的孔隙度就是指其中空间的比例。但需要注意的是，孔隙度与渗透率是不同的。渗透率衡量的是水渗透物质的难易程度，它取决于与单个空隙以及连接孔隙间裂缝的大小。Muchofthewaterinasampleofwater-saturatedsedimentorrockwilldrainfromitifthesampleisputinasuitabledryplace.Butsomewillremain,clingingtoallsolidsurfaces.Itisheldtherebytheforceofsurfacetensionwithoutwhichwaterwoulddraininstantlyfromanywetsurface,leavingittotallydry.Thetotalvolumeofwaterinthesaturatedsamplemustthereforebethoughtofasconsistingofwaterthatcan,andwaterthatcannot,drainaway.当充满水分的沉淀物或者岩石样本被放置在适宜的干燥环境中时，大部分的水分会流失，但仍有部分水会继续附着在坚实的表面上。要不是因为表面张力，这些水分也会立刻蒸发，仅留下完全干燥的样本。因此，试验样本的含水量既包括可以流干的水，也包括不能流干的水。Therelativeamountofthesetwokindsofwatervariesgreatlyfromonekindofrockorsedimenttoanother,eventhoughtheirporositiesmaybethesame.Whathappensdependsonporesize.Iftheporesarelarge,thewaterinthemwillexistasdropstooheavyforsurfacetensiontohold,anditwilldrainaway;butiftheporesaresmallenough,thewaterinthemwillexistasthinfilms,toolighttoovercometheforceofsurfacetensionholdingtheminplace;thenthewaterwillbefirmlyheld.这两种水的相对含量因岩石或沉积物种类不同而改变，即便它们有相同比例的孔隙，还取决于孔隙的大小。如果孔隙很大，其中的水会形成水滴，太重足以克服吸引它的表面张力，就会流走；但如果孔隙够小，水会像薄膜一样，太轻无法克服表面张力，从而稳稳地附着在孔隙表面上。第1题：Whichofthefollowingcanbeinferredfromparagraph1aboutthegroundthatwewalkon?A：Itcannotholdrainwaterforlongperiodsoftime.B：Itpreventsmostgroundwaterfromcirculating.C：Ithasthecapacitytostorelargeamountsofwater.D：Itabsorbsmostofthewateritcontainsfromrivers.解析：以下哪一项能够从第一段推出与我们走的路地有关？（InferenceQuestion）a)它不能长时间储存水。b)它阻止了大部分地下水进行水循环。c)它有能力储存大量的地下水。d)它大部分的水从河流中吸收。根据“groundthatwewalkon”定位到段落最后一句话“Atfirstthoughtitseemsincrediblethattherecanbeenoughspaceinthe“solid”groundunderfootto