托福 新托福 24 - Lake Water
题目
1 2 3 4 5 6 7 8 9 10
3.Which of the following can be inferred from paragraph 2 about the movement of water into a lake?
  • A.Heavy rain accounts for most of the water that enters into lakes.
  • B.Rainfall replaces approximately the amount of water lost through evaporation.
  • C.Overland flow into lakes is reduced by the presence of forests.
  • D.Seepage has a smaller effect on water level than any other input.
  • 正确答案:
    答案解析:
    答题统计
    答题统计

    登录 后才可以查看答案解析,还没有账号?

    还没有账号?马上 注册 >>

    阅读原文 中文译文

    Where does the water in a lake come from, and how does water leave it? Water enters a lake from inflowing rivers, from underwater seeps and springs, from overland flow off the surrounding land, and from rain falling directly on the lake surface. Water leaves a lake via outflowing rivers, by soaking into the bed of the lake, and by evaporation. So much is obvious.

    The questions become more complicated when actual volumes of water are considered: how much water enters and leaves by each route? Discovering the inputs and outputs of rivers is a matter of measuring the discharges of every inflowing and outflowing stream and river. Then exchanges with the atmosphere are calculated by finding the difference between the gains from rain, as measured (rather roughly) by rain gauges, and the losses by evaporation, measured with models that correct for the other sources of water loss. For the majority of lakes, certainly those surrounded by forests, input from overland flow is too small to have a noticeable effect. Changes in lake level not explained by river flows plus exchanges with the atmosphere must be due to the net difference between what seeps into the lake from the groundwater and what leaks into the groundwater. Note the word "net": measuring the actual amounts of groundwater seepage into the lake and out of the lake is a much more complicated matter than merely inferring their difference.

    Once all this information has been gathered, it becomes possible to judge whether a lake’s flow is mainly due to its surface inputs and outputs or to its underground inputs and outputs. If the former are greater, the lake is a surface-water-dominated lake; if the latter, it is a seepage-dominated lake. Occasionally, common sense tells you which of these two possibilities applies. For example, a pond in hilly country that maintains a steady water level all through a dry summer in spite of having no streams flowing into it must obviously be seepage dominated. Conversely, a pond with a stream flowing in one end and out the other, which dries up when the stream dries up, is clearly surface water dominated.

    By whatever means, a lake is constantly gaining water and losing water: its water does not just sit there, or, anyway, not for long. This raises the matter of a lake’s residence time. The residence time is the average length of time that any particular molecule of water remains in the lake, and it is calculated by dividing the volume of water in the lake by the rate at which water leaves the lake. The residence time is an average; the time spent in the lake by a given molecule (if we could follow its fate) would depend on the route it took: it might flow through as part of the fastest, most direct current, or it might circle in a backwater for an indefinitely long time.

    Residence times vary enormously. They range from a few days for small lakes up to several hundred years for large ones; Lake Tahoe, in California, has a residence time of 700 years. The residence times for the Great Lakes of North America, namely, Lakes Superior, Michigan, Huron, Erie, and Ontario, are, respectively, 190,100,22,2.5, and 6 years. Lake Erie’s is the lowest: although its area is larger than Lake Ontario’ s, its volume is less than one-third as great because it is so shallow-less than 20 meters on average.

    A given lake’s residence time is by no means a fixed quantity. It depends on the rate at which water enters the lake, and that depends on the rainfall and the evaporation rate. Climatic change (the result of global warming?) is dramatically affecting the residence times of some lakes in northwestern Ontario, Canada. In the period 1970 to 1986, rainfall in the area decreased from 1,000 millimeters to 650 millimeters per annum, while above-average temperatures speeded up the evapotranspiration rate (the rate at which water is lost to the atmosphere through evaporation and the processes of plant life).
    The result has been that the residence time of one of the lakes increased from 5 to 18 years during the study period. The slowing down of water renewal leads to a chain of further consequences; it causes dissolved chemicals to become increasingly concentrated, and this, in turn, has a marked effect on all living things in the lake.

    湖里的水从哪里来,又怎么流出的呢?湖中的水来自于河流的水,地下渗入的水和泉水,从四周地面流进来的水,还有直接降到湖面的雨水。湖中的水通过向外流的河流,渗透进河床以及蒸发离开湖泊。这些都是显而易见的。 当考虑到实际的水流量时就会变得更加复杂:水通过上述方式流进和流出的量是多少?了解河流的流进量和流出量是一件测量每一条流入和流出的河流其容量的事情。 和大气的交换是通过发现雨水中得到的水(通过雨量器大致测得)和蒸发损失的水(通过准确测量其他的水损失来源的模式测得)的差别来计算的。对于大多数的湖来说,特别是那些被森林环绕的湖,地面流入的水太少了以至于几乎没有能够感觉到的影响。河水和大气水量变化不能解释湖中水平面的变化, 是因为渗入湖中的地下水和渗出的地下水的净值不同。注意一下“净值”这个词:测量真正渗入和渗出湖中的地下水量比仅仅推断它们的不同要复杂的多。 一旦所有的这些信息都收集到了,那么判断一个湖的流量是由表面输入或输出决定的还是由地下水进出量决定的就变得可能了。如果主要是前者决定,那么湖泊就是一个表面水主导的湖,如果是后者,那么它就是一个渗透水主导的湖。有时候,常识会告诉你这两种可能性哪一种在起作用。 比如说一个丘陵地区的池塘在整个干燥的夏天尽管没有溪水注 入仍能保持稳定的水位,那么显然它是一个渗透水主导的池塘。相反,一个池塘有河流进和流出,随河水的干枯而干枯,那么这就是一个表面水主导的池塘。 不管怎么说,湖泊是在不停地流进和流出水;它的水不会停留在湖里,或者说不会长久的停留。 这个会增加湖泊的停留时间。 停留时间指的是特定水分子在湖中停留的平均时间长度,是通过计算湖水流量流出湖泊的速度计算出来的。停留时间是一个平均数;湖中特定分子(如果我们可以追踪它的路线的话)花费的时间取决于它的路线:它可能是最快最直接的水流的那一部分流过,或者它可能在在逆流中无限长的时间里打圈。 停留时间变化非常的大, 从小型湖的几天到大型湖泊的几百年。 加利福尼亚州的塔霍湖的停留时间就长达 700 年。北美五大湖也就是苏必利尔湖、密歇根湖、休伦湖、伊利湖和安大略湖的停留时间分别是 190 年、100 年、22 年、2.5 年和 6 年。伊利湖是最短的:尽管它的面积比安大略湖要大, 它的容量不及后者的三分之一, 因为它的平均深度还不到 20 米。 给定的湖泊的停留时间绝不是一个确定的值。 它取决于水流进湖的速度, 而这个速度取决于降雨量和蒸发速度。气候变化(全球变暖的结果?)严重影响着加拿大安大略湖西北部一些湖泊的停留时间。在 1970 年到 1986 年间,这个地区的降雨量由每年 1 000 毫米降到了 650 毫米, 而同时平均温度的上升加快了蒸散率 (这个速率指的是水蒸发到大气的速率以及植物生命的过程) 。结果是,在研究期间其中一个湖的停留时间从 5 年增加到 18 年。湖水的更新变慢导致了一系列后果;它使得溶解的化学物质不断变浓,这样反过来会对湖中的生物造成显著的影响。

    留言区中有很多我们对问题的解答喔, 登录后可以查看

    还没有账号?马上 注册 >>

    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
    • 以沫
      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
    • wx_6697
      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
    • wx_6697
      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
    • wx_8861
      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
    • wx_6697
      求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
    • 与托福的斗争史
      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
    • wx_100
      请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
    • wx xxxxx
      请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
    • haiyuqiao
      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
    • wx_2065
      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.