托福阅读tpo 1 Groundwater 地下水原题解析.doc

阅读原文：?Groundwater is the word used to describe water that saturates the ground, filling all the available spaces. By far the most abundant type of groundwater is meteoric water; this is the groundwater that circulates as part of the water cycle. Ordinary meteoric water is water that has soaked into the ground from the surface, from precipitation (rain and snow) and from lakes and streams. There it remains, sometimes for long periods, before emerging at the surface again. At first thought it seems incredible that there can be enough space in the solid ground underfoot to hold all this water.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。The necessary space is there, however, in many forms. The commonest spaces are those among the particlessand grains and tiny pebblesof loose, unconsolidated sand and gravel. Beds of this material, out of sight beneath the soil, are common. They are found wherever fast rivers carrying loads of coarse sediment once flowed. For example, as the great ice sheets that covered North America during the last ice age steadily melted away, huge volumes of water flowed from them. The water was always laden with pebbles, gravel, and sand, known as glacial outwash, that was deposited as the flow slowed down.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。The same thing happens to this day, though on a smaller scale, wherever a sediment-laden river or stream emerges from a mountain valley onto relatively flat land, dropping its load as the current slows: the water usually spreads out fanwise, depositing the sediment in the form of a smooth, fan-shaped slope. Sediments are also dropped where a river slows on entering a lake or the sea, the deposited sediments are on a lake floor or the seafloor at first, but will be located inland at some future date, when the sea level falls or the land rises; such beds are sometimes thousands of meters thick.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。In lowland country almost any spot on the ground may overlie what was once the bed of a river that has since become buried by soil; if they are now below the waters upper surface (the water table), the gravels and sands of the former riverbed, and its sandbars, will be saturated with groundwater.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。So much for unconsolidated sediments. Consolidated (or cemented) sediments, too, contain millions of minute water-holding pores. This is because the gaps among the original grains are often not totally plugged with cementing chemicals; also, parts of the original grains may become dissolved by percolating groundwater, either while consolidation is taking place or at any time afterwards. The result is that sandstone, for example, can be as porous as the loose sand from which it was formed.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。Thus a proportion of the total volume of any sediment, loose or cemented, consists of empty space. Most crystalline rocks are much more solid; a common exception is basalt, a form of solidified volcanic lava, which is sometimes full of tiny bubbles that make it very porous.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。The proportion of empty space in a rock is known as its porosity. But note that porosity is not the same as permeability, which measures the ease with which water can flow through a material; this depends on the sizes of the individual cavities and the crevices linking them.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。Much of the water in a sample of water-saturated sediment or rock will drain from it if the sample is put in a suitable dry place. But some will remain, clinging to all solid surfaces. It is held there by the force of surface tension without which water would drain instantly from any wet surface, leaving it totally dry. The total volume of water in the saturated sample must therefore be thought of as consisting of water that can, and water that cannot, drain away.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。The relative amount of these two kinds of water varies greatly from one kind of rock or sediment to another, even though their porosities may be the same. What happens depends on pore size. If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.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：Which of the following can be inferred from paragraph 1 about the ground that we walk on?A：It cannot hold rainwater for long periods of time.B：It prevents most groundwater from circulating.C：It has the capacity to store large amounts of water.D：It absorbs most of the water it contains from rivers.解析：以下哪一项能够从第一段推出与我们走的路地有关？（Inference Question）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“ground that we walk on”定位到段落最后一句话“At first thought it seemsincrediblethatthere can be enough spacein the “solid” ground underfootto hold all this water.”意思是：一开始很难想象我们脚下的地有足够的空间容下这些水。选项一错，倒数第二句“There it remains, sometimesfor long periods, before emerging at the surface again.”For long periods长时间；remain v.保持；emerge v.出现；选项二错，段落第二句“By far themostabundanttype of groundwater is meteoric water; this is the groundwater that circulates as part of thewater cycle.”意思是：现在最丰富的地下水类型是雨水；这些雨水是进入水循环的那部分；by far最；abundant adj.富足；circulate v.循环；选项四错，段落第三句“Ordinary meteoric water is water that has soaked into the groundfrom the surface,fromprecipitationandfrom lakes and streams.”意思是：平常的雨水都是那些从地表、降水和河流湖泊中渗入地下的水。soak v.渗透；precipitationn.降雨，降雪；第2题：The word incredible in the passage is closest in meaning toA：confusingB：comfortingC：unbelievableD：interesting解析：与单词incredible在文章中意思最接近的是（Vocabulary Question）a)Confusing（令人迷惑的）b)Comforting（安慰人的）c)Unbelievable（难以置信的）d)Interesting（有趣的）查字典! Incredible adj.难以置信的；in-否定前缀；cred词根，意思“信用”；-ible形容词后缀；un-否定前缀；believe v.相信；-able形容词后缀；incredible和unbelievable也是常考同义词对子。第3题：The word out of sight in the passage is closest in meaning toA：far awayB：hiddenC：partly visibleD：discovered解析：与单词“out of sight”在文中意思最接近的是（Vocabulary Question）a)Far away（遥远）b)Hidden（隐藏）c)Partly visible （部分可见）d)Discovered（发现的）sight n.眼界；out of sight眼界之外；有一个俗语：Out of sight, out of mind;眼不见心不烦；隐藏的肯定看不见；far away遥远也可以看得见，比如夜晚空中的星星；第4题：According to paragraph 2, where is groundwater usually found?A：Inside pieces of sand and gravelB：On top of beds of rockC：In fast rivers that are flowing beneath the soilD：In spaces between pieces of sediment解析：根据第二段，通常在哪里能找到地下水？（Factual Information Question）a)在沙子和沙砾碎片中b)在岩石床的上面c)在泥土下快速流动的河水中d)在沉积物碎片之间的空隙根据段落前两句话“The necessary space is there, however, in many forms. The commonest spaces arethose among the particles-sand grains and tiny pebbles-of loose, unconsolidated sand and gravel.”意思是：必须的空间就在那儿，尽管形式多样。最平常的空间是那些松散不坚固的沙子和沙砾微粒（砾子和小石子）间的空隙。Particle n.粒子；grain n.粒子；pebble n.小鹅卵石；gravel n.沙砾；loose adj.松的；consolidate adj.坚固的；unconsolidated adj.不坚固的；选项一错，不是在sand和gravel里面，而是在它们的缝隙里面；those among the particles；those代表的是space；选项二和三也都错在不是空隙；只有选项四有spaces，并且段落第四句“They are found wherever fast rivers carryingloads of coarse sedimentonce flowed.”第5题：The phrase glacial outwash in the passage refers toA：fast riversB：glaciersC：the huge volumes of water created by glacial meltingD：the particles carried in water from melting glaciers解析：用语glacial outwash在文中指（Reference Question）a)快速河流b)冰川c)冰川融化形成大量的水d)冰川融化的水中带的微粒回到原句“The water was always laden with pebbles, gravel,andsand,known as glacial outwash, that was deposited as the flow slowed down.”意思是：水携带卵石、沙砾和沙子，这些被称为glacial outwash，水流缓慢时沉积下来。根据Known as用语的意思就能判断出glacial outwash指的是pebbles, gravel, and sand而这三样东西都由水携带，水又是冰川融化而得，所以答案选第四项；Known as被称之为;be laden with装满。；deposit v.沉淀；slow down慢下来；第6题：All of the following are mentioned in paragraph 3 as places that sediment-laden rivers can deposit their sediments EXCEPTA：A mountain valleyB：Flat landC：A lake floorD：The seafloor解析：以下地点在第三段中都提到作为河流沉积沉积物的地方，除了（Negative Factual Information Question）a)山谷中b)平地c)湖底d)海底段落第一句“The same thing happens to.emerges from a mountain valley onto relatively flat land,dropping its loadas the current slows”所以平地是有的；再看第二句“Sediments are also dropped where.the deposits sediments areon a lake floor or the seafloor at first.”因此，湖底和海底也行；山谷是没有的，文章只说了河流会从山谷流到平地，没说过是否在山谷中沉淀。Emerge v.出现；drop v.放下；spread out展开；第7题：The word overlie in the passage is closest in meaning toA：coverB：changeC：separateD：surround解析：与单词overlie在文章中意思最接近的是（Vocabulary Question）a)Cover（覆盖）b)Change（改变）c)Separate （分离）d)Surround（包围）查字典，overlie的意思是“躺在。上面”；毫无疑问cover是组接近的。Overlie和cover都只有在上方的意思。Surround是四面八方，这样才能称作包围，所以不对。第8题：The phrase So much for in the passage is closest in meaning toA：that is enough aboutB：now let us turn toC：of greater concern areD：this is related to解析：与用语“so much for”在文章中意思最接近的是（Vocabulary Question）a)That is enough about (关于。已经足够了)b)Now let us turn to（现在，我们换一个话题到。）c)Of greater concern are(更担心的是)d)This is related to（这与。有关）so much for .关于已经很多了。只有This is enough about是匹配的。经常在转换话题的时候都会用这两句话：Thats so much for A./ Thats enough about A.；第9题：The word plugged in the passage is closet in meaning toA：washedB：draggedC：filled upD：soaked through解析：与单词plugged在文中意思最接近的是（Vocabulary Question）a)Washed（冲刷）b)Dragged（拖，拉）c)Filled up（充满）d)Soaked through（渗入）plug v.堵，赛，插上；含义与充满是一样的。第10题：According to paragraphs 6 and 7, why is basalt unlike most crystalline forms of rock?A：It is unusually solid.B：It often has high porosity.C：It has a low proportion of empty space.D：It is highly permeable.解析：根据第六段和第七段，为什么basalt与其它晶体岩石不一样？（Factual Information Question）a)它不同寻常地坚固。b)它通常有高多孔性。c)它的空隙空间比例很低。d)它的浸透性很高。回到第六段第二句“Most crystalline rocks are much more solid; a common exception is basalt, a form of solidified volcanic lava, which is sometimesfull of tiny bubbles that make it very porous.”意思是：大多数晶体岩石都很坚固；有一个特例是玄武岩，这是一种固化的火山熔岩，它有时充满了小的气泡使得它变得很多空。Solid adj.坚固的；solidify v.固化；lava n.熔岩；bubble n.气泡；porous adj.多孔的；exception n.特例；exceptional adj.异常的第11题：What is the main purpose of paragraph 7?A：To explain why water can flow through rockB：To emphasize the large amount of empty space in all rockC：To point out that a rock cannot be both porous and permeableD：To distinguish between two related properties of rock解析：第七段的主要目的是什么？（Rhetorical Purpose Question）a)为了解释为什么水能够流过岩石b)为了强调岩石中大量的空隙空间c)为了指出一块岩石很难即多孔又能渗透d)区别两种相关的岩石性质第七段重要解释区分了permeability和porosity这两种岩石性质。Porosity是孔隙度，即一块岩石中空隙空间的比例；permeability是渗透性，指的水穿过一种物质的难易程度。第12题：Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.A：Surface tension is not strong enough to retain drops of water in rocks with large pores but it strong enough to hold on to thin films of water in rocks with small pores.B：Water in rocks is held in place by large pores and drains away from small size pores through surface tension.C：Small pores and large pores both interact with surface tension to determine whether a rock will hold water as heavy drops or as a thin film.D：If the force of surface tension is too weak to hold water in place as heavy drops, the water will continue to be held firmly in place as a thin film when large pores exist.解析：以下哪一项能表达出高亮句子的精华核心含义？错误选项改变重要含义或者遗漏精华信息。（Sentence Simplification Question）If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.如果空隙很大，它们中的水会以小水滴的形式存在，这样太重了以至于表面拉力不够，于是水会流干；但是如果空隙足够小，它们中的水会以薄片的形式存在，这样太轻以至于克服不了表面拉力，于是水就被紧紧地抓住了。句子的主干是：If the pores are large, the water.; If the pores are small enough, the water.;Too to太而不能；hold v.抓住；drain away流干；overcome v.克服；tension n.拉力；force n.力量；exist as以。存在；a)表面拉力没有强到可以留住岩石大空隙中的水滴，但足够留下小空隙中的薄片。b)岩石中的水通过大孔隙留住，通过表面拉力从小空隙流干。c)小空隙和大孔隙与表面张力相互作用以决定一块岩石是能留住水滴还是水薄片。d)如果表面张力太弱而抓不住重水滴，水会接着以薄片的形式被牢牢抓住当大孔隙存在时。第13题：Look at the four squares that indicate where the following sentence could be added to the passage. Where would the sentence best fit?What, then, determines what proportion of the water stays and what proportion drains away?解析：Look at the four squaresthat indicate where the following sentence could be added to the passage.What, then , determines what proportion of the water stays and what proportion drains away?那，是什么决定哪部分水留下，哪部分水流干？Proportion n.部分；drain away流干看大句子的第一反应便是句子之后肯定要有文章内容回答这个问题。发现只有第九段回答了此问题，所以答案是第四个插入口。第14题：Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.Much of the ground is actually saturated with water.A. Sediments that hold water were spread by glaciers and are still spread by rivers and streams.B. Water is stored underground in beds of loose sand and gravel or in cemented sediment.C. The size of a saturated rocks pores determines how much water it will retain when the rock is put in a dry place.D. Groundwater often remains undergroun