『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 12 Passage 3阅读练习，TPO/Official 12 Passage 3原文答案解析，TPO/Official 12 Passage 3阅读原文练习音频翻译。

托福TPO/Official 12 Passage 3阅读原文题目答案及解析-新东方托福官方网校手机版

在沙漠地区，并不是完全没有降雨，但它变化很大。

Rainfall is not completely absent in desert areas, but it is highly variable.

每年4英寸的降雨量经常被用来定义沙漠的界限。

An annual rainfall of four inches is often used to define the limits of a desert.

降雨对沙漠地表水和地下水资源的影响，跟地形地貌关系较大。

The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms.

可以集水的平原和洼地是常见的地貌特征，但它们只占地貌的一小部分。

Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.

令人惊讶的是，干旱地区包含了一些世界上最大的河流系统，如澳大利亚的墨累-达令河、北美的里约格兰德河、亚洲的印度河和非洲的尼罗河。

Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa.

这些河流和水系被称为“外源的”，因为它们的源头位于干旱地区之外。

These rivers and river systems are known as “exogenous” because their sources lie outside the arid zone.

它们对于维持世界上一些最干旱地区的生命至关重要。

They are vital for sustaining life in some of the driest parts of the world.

例如，几个世纪以来，尼罗河、底格里斯河和幼发拉底河每年的洪水，给下游山谷的居民带来了肥沃的淤泥和水。

For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, have brought fertile silts and water to the inhabitants of their lower valleys.

今天，河流排放越来越多地受到人为干预的控制，这就需要国际流域协议。

Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements.

土耳其的阿塔图尔克水坝和其他水坝的蓄水已经大大减少了幼发拉底河的流量，可能会给叙利亚和伊拉克带来严重后果。

The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.

外源河流的流量随季节而变化。

The flow of exogenous rivers varies with the season.

长河的沙漠部分在降雨到沙漠之外的几个月后才会发生反应，所以流量高峰可能是在旱季。

The desert sections of long rivers respond several months after rain has fallen outside the desert, so that peak flows may be in the dry season.

这对于灌溉是有用的，但是与正常生长季节相比，旱季的高温、低湿度和不同的白昼长度会给一些作物带来困难。

This is useful for irrigation, but the high temperatures, low humidities, and different day lengths of the dry season, compared to the normal growing season, can present difficulties with some crops.

源自干旱地区的有规律的流动的河流和小溪被称为“内源的（河流）”。

Regularly flowing rivers and streams that originate within arid lands are known as “endogenous.”

它们通常由地下水泉提供养分，其中许多发源自石灰岩山丘，比如摩洛哥的阿特拉斯山脉。

These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco.

玄武岩也为泉水提供了支撑，尤其是在约旦和叙利亚边境的阿拉伯半岛。

Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border.

内源河流往往不入海，而是流入内陆盆地，在那里水分蒸发或消失在地下。

Endogenous rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground.

大多数沙漠河床通常是干涸的，但它们偶尔会吸收大量的水流和沉积物。

Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.

与湖泊和河流等地表储藏相比，沙漠含有大量地下水。

Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers.

但是，只有一小部分地下水进入水循环——供给溪流，维持湖泊水位，并通过地表水流和雨水补充（或再填充）。

But only a small fraction of groundwater enters the hydrological cycle--feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater.

近年来，地下水已成为沙漠居民日益重要的淡水来源。

In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers.

联合国环境规划署和世界银行为调查干旱土地的地下水资源和开发适当的开采技术提供了资金。

The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques.

这样的计划是非常必要的，因为在许多干旱地区，人们对地下水资源的范围只有一个模糊的概念。

Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources.

但是，众所周知，地下水的分布是不均匀的，而且大部分都在很深的地方。

It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.

地下水储存在岩石和未固结（未凝固）沉积物的孔隙空间和接缝中，或通过裂缝和风化加宽的开口中。

Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering.

含水的岩石或沉积物被称为“含水层”。

The water-saturated rock or sediment is known as an “aquifer.”

由于它们是多孔的，沉积岩，如砂岩和砾岩，是地下水的重要潜在来源。

Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater.

当石灰岩的接缝和裂缝扩大形成洞穴时，大量的水也可能被储存在石灰岩中。

Large quantities of water may also be stored in limestones when joints and cracks have been enlarged to form cavities.

大多数石灰岩和砂岩含水层既深又广，但可能含有未补给的地下水。

Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters that are not being recharged.

大多数砂石层的浅层含水层产量较低，但它们可以迅速得到补充。

Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged.

一些深层含水层被称为“化石”水。

Some deep aquifers are known as “fossil” waters.

“化石”一词描述的是这些水已经存在了几千年。

The term “fossil” describes water that has been present for several thousand years.

这些含水层在一万多年前就饱和了，再充一次水需要更长的时间。

These aquifers became saturated more than 10,000 years ago longer being recharged.

水在含水层中并不是静止不动的，而是会从泉水中渗出或渗入其他含水层。

Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers.

运动的速度可能非常缓慢：在印度河平原，经过70年的开发，含盐地下水的运动仍然没有达到平衡。

The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwaters has still not reached equilibrium after 70 years of being tapped.

地下水的矿物含量通常随深度增加而增加，但即使是很浅的含水层也可能是高盐的。

The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.

Which of the following statements about annual rainfall can be inferred from paragraph 1?

The word “drastically” in the passage is closest in meaning to

In paragraph 2, why does the author mention the Ataturk and other dams in Turkey?

According to paragraph 2, which of the following is true of the Nile River?

The word “dwellers” in the passage is closest in meaning to

Paragraph 5 supports all of the following statements about the groundwater in deserts EXCEPT:

The word “fractures” in the passage is closest in meaning to

According to paragraph 6, which of the following statements about aquifers in deserts is true?

According to paragraph 6, the aquifers called “fossil” waters

The word “immobile” in the passage is closest in meaning to

The passage supports which of the following statements about water in the desert?

Look at the four squares  that indicate where the following sentence could be added to the passage. These sudden floods provide important water supplies but can also be highly destructive.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

Directions: Select from the seven sentences below, the two sentences that correctly characterize endogenous rivers and the three sentences that correctly characterize exogenous rivers. Drag each sentence you select into the appropriate column of the table. Two of the sentences will NOT be used. This question is worth 3 points.

Water in the Desert Rainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape. Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as “exogenous” because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, have brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq. The flow of exogenous rivers varies with the season. The desert sections of long rivers respond several months after rain has fallen outside the desert, so that peak flows may be in the dry season. This is useful for irrigation, but the high temperatures, low humidities, and different day lengths of the dry season, compared to the normal growing season, can present difficulties with some crops. Regularly flowing rivers and streams that originate within arid lands are known as “endogenous.” These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border.  Endogenous rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground.  Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.  Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers.  But only a small fraction of groundwater enters the hydrological cycle--feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths. Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an “aquifer.” Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in limestones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as “fossil” waters. The term “fossil” describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago longer being recharged. Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwaters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.