所谓语境记忆单词Remember by the context ，也就是将单词置于句子或课文中加以记忆的策略。而在应对托福词汇单词记忆的时候，由于其词汇量大，同时，我们除了学会词汇的拼写之外，还要更好的理解其的使用方法。那么，相信这样的语境记忆方法就是非常的适合了。那么，在以下内容中就为大家带来托福TPO阅读重点词汇语境记忆资料，希望能为大家的备考带来帮助。
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 Programmer 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 and are no 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.
托福单词记忆
Annual 每年的
原文：An annual rainfall of four inches is often used to define the limits of a desert. 通常一年以内降雨次数少于4次是定义沙漠的限定条件。
强化记忆：
The kind of plant is a hardy annual. 这种植物是耐寒的一年生植物。
His essay is copied from a college annual. 他的论文是从一本大学年刊上抄下来的。
Exogenous外生的;外流河
原文：These rivers and river systems are known as "exogenous" because their sources lie outside the arid zone. 这些河流被称作和所在的流域因为河的源头在干旱地区以外而被称为“外流河”。
强化记忆：
Disorders of old age are generally not exogenous. 老年疾病通常都不是起于外因的。
Changes of government can be regarded as exogenous events too. 政府重组同样可被看作是一外援事件。
Sustain 维持;支持
原文：They are vital for sustaining life in some of the driest parts of the world. 他们对于全世界沙漠地区的生命的存活至关重要。
强化记忆：
During the war we had just enough food to sustain us. 战争期间，我们的食物仅够维持生活。
These four posts sustain the entire building. 这四根柱子支撑着整座建筑物。
Silt 淤泥;泥沙
原文：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. 几个世纪以来，尼罗河每年都会定期泛滥。举个例子，幼发拉底河和底格里斯河都会把大量的肥沃的泥沙和水源带给下游低洼地带的居民。
强化记忆：
The water contains fine silt. 水里含有细泥沙。
The river deposited silt at its mouth. 河口沉积了淤泥。
Intervention干涉;介入
原文：Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. 现在，河水的流量越来越多的受到人类的干涉，产生了国际性的河流流域的协议。
强化记忆：
The incident was used as a pretext for intervention in the area. 这次事件成了干涉那个地区的借口。
The government’s intervention in this dispute will not help. 政府对这场争论的干预不会起作用。
Drastically 剧烈地;显著地
原文：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. 阿卡杜克水坝以及其他一些建在土耳其境内的大坝就极大的减少了幼发拉底河的径流量，潜移默化的给叙利亚河和伊拉克造成了严重的后果。
强化记忆：
Next year’s budget will have to be drastically pruned. 下一年度的预算将大幅度消减。(prune减少)
Social work services have been cut back drastically. 社会工作服务已经大大减少了。
Endogenous 内流河;内生的
原文：Regularly flowing rivers and streams that originate within arid lands are known as "endogenous." 通常发源地在干旱地区的河流和溪水被称为“内流河”。
强化记忆：
Every model includes exogenous and also endogenous variables which must be estimated. 每一个模型都包括需要估计的外生变量和内生变量。
Endogenous rhythm 内在周律
Endogenous metabolism 内新陈代谢
Basaltic 玄武岩的
原文：Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. 玄武岩石也提供源头水，比较著名的就是约旦和叙利亚交接的Jabal Al-Arab.
强化记忆：
Basaltic is the commonest volcanic rock. 玄武岩是最普通的火山岩。
Basaltic magma is fluid. 玄武岩岩浆是流动的。
Evaporate 蒸发
原文：Endogenous rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. 内流河通常都不会到达大海而是注入内陆的低地的同时蒸发或者消失在地表。
强化记忆：
If you heat the water, it will evaporate. 你要是把水加热，水会蒸发的。
He was afraid his savings would evaporate overnight. 他担心他的储蓄隔夜就蒸发了。
Hydrological 水文学的
原文：But only a small fraction of groundwater enters the hydrological cycle不过只有一小部分地下水参与了河流的水循环。
强化记忆：
In this system, the mode of hydrological information transmission is very important. 水情信息的传输方式是该系统的重要部分。
The correct method of prevention and control should naturally start with the improvement of the hydrological environment. 正确的防治办法，自然应该从改善水文环境入手。
Extraction 抽出;拔出;血统
原文：The United Nations Environment Programmer and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. 美国国家环境总署和世界银行开始拨款尝试调查统计干旱地区的地下水资源并发展合适的开采技术。
强化记忆：
The local economy is overwhelmingly dependent on oil and gas extraction. 当地经济过于依赖石油和天然气的开采。
He married a young lady of Indian extraction. 他娶了一位年轻的印度裔女子。
Conglomerate 砾石;凝结
原文：Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. 因为沉积岩的多孔性，比如砂岩和砾岩，都是地下水的重要潜在源头。
强化记忆：
Sandstone and conglomerate are the consolidated equivalent of sand and gravel. 砂岩和砾岩分别是砂和砾石固结的产物。
Tap开发;发掘;水龙头
原文：The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwater has still not reached equilibrium after 70 years of being tapped. 在印度平原，流动的含盐地下水在开发了70年以后依旧不能达到平静。
强化记忆：
Connect the hose to the tap and turn on the tap. 把水管接在龙头上，打开水龙头。
Is the tap water safe to drink? 喝这自来水安全吗?
Equilibrium平静;均衡
原文：The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwater has still not reached equilibrium after 70 years of being tapped. 在印度平原，流动的含盐地下水在开发了70年以后依旧不能达到平静。
强化记忆：
For the economy to be in equilibrium, income must equal expenditure. 经济要达到平衡，收支必须平衡。
Change in the world around us disturbs our inner equilibrium. 我们周围世界的变化扰乱了我们内心的平静。
Saline 盐的;含盐的
原文：The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwater has still not reached equilibrium after 70 years of being tapped. 在印度平原，流动的含盐地下水在开发了70年以后依旧不能达到平静。
强化记忆：
He is on a saline drip. 他正在输盐水。
Wash the lenses in saline solution. 用盐溶液清洗镜片。
