篇一：托福阅读OG完整版三【附完整版】
智课网TOEFL备考资料
托福阅读OG完整版三【附完整版】
摘要： 备战托福阅读的备考资料里面除了TPO，就要数OG了，之前我们已经将全套的托福阅读ＴＰＯ内容分享给了大家，今天小编就来为大家爱介绍下由ＥＴＳ官网提供的完整版ＯＧ内容，希望对大家的托福考试会有一定的帮助。
托福 阅读OG完整版三：DESERT FORMATION (OG)
托福阅读 OG完整版三：DESERT FORMATION (OG)
The deserts, which already occupy approximately a fourth of the Earth's land surface, have in recent decades been increasing at an alarming pace. The expansion of desertlike conditions into areas where they did not previously exist is called desertification. It has been estimated that an additional one-fourth of the Earth's land surface is threatened by this process.
Desertification is accomplished primarily through the loss of stabilizing natural vegetation and the subsequent accelerated erosion of the soil by wind and water. In some cases the loose soil is blown completely away, leaving a stony surface. In other cases, the finer particles may be removed, while the sand-sized particles are accumulated to form mobile hills or ridges of sand.Even in the areas that retain a soil cover, the reduction of vegetation typically results in the loss of the soil's ability to absorb substantial quantities of water. The impact of raindrops on the loose soil tends to transfer fine clay particles into the tiniest soil spaces, sealing them and producing a surface that allows very little water penetration. Water absorption is greatly reduced;consequently runoff is increased, resulting in accelerated
erosion rates. The gradual drying of the soil caused by its diminished ability to absorb water results in the further loss of vegetation, so that a cycle of progressive surface deterioration is established.
In some regions, the increase in desert areas is occurring largely as the result of a trend toward drier climatic conditions. Continued gradual global warming has produced an increase in aridity for some areas over the past few thousand years. The process may be accelerated in subsequent decades if global warming resulting from air pollution seriously increases.
There is little doubt, however, that desertification in most areas results primarily from human activities rather than natural processes. The semiarid lands bordering the deserts exist in a delicate ecological balance and are limited in their potential to adjust to increased environmental pressures.Expanding populations are subjecting the land to increasing pressures to provide them with food and fuel. In wet periods, the land may be able to respond to these stresses. During the dry periods that are common phenomena along the desert margins, though, the pressure on the land is often far in excess of its diminished capacity, and desertification results.
Four specific activities have been identified as major contributors to the desertification processes: overcultivation, overgrazing, firewood gathering, and overirrigation. The cultivation of crops has expanded into progressively drier regions as population densities have grown. These regions are especially likely to have periods of severe dryness, so that crop failures are common.
Since the raising of most crops necessitates the prior removal of the natural vegetation, crop failures leave extensive tracts of land devoid of a plant cover and susceptible to wind and water erosion.The raising of livestock is a major economic activity in semiarid lands, where grasses are generally the dominant type of natural vegetation. The
consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. This is usually followed by the drying of the soil and accelerated erosion.
Firewood is the chief fuel used for cooking and heating in many countries. The increased pressures of expanding populations have led to the removal of woody plants so that many cities and towns are surrounded by large areas completely lacking in trees and shrubs. The increasing use of dried animal waste as a substitute fuel has also hurt the soil because this valuable soil conditioner and source of plant nutrients is no longer being returned to the land.
The final major human cause of desertification is soil salinization resulting from over-irrigation. Excess water from irrigation sinks down into the water table. If no drainage system exists, the water table rises, bringing dissolved salts to the surface. The water evaporates and the salts are left behind, creating a white crustal layer that prevents air and water from reaching the underlying soil.
The extreme seriousness of desertification results from the vast areas of land and the tremendous numbers of people affected, as well as from the great difficulty of reversing or even slowing the process. Once the soil has been removed by erosion, only the passa
Paragraph 1: The deserts, which already occupy approximately a fourth of the Earth's land surface, have in recent decades been increasing at an alarming pace. The expansion of desert-like conditions into areas where they did not previously exist is called desertification. It has been estimated that an additional one-fourth of the Earth's land surface is threatened by this process.
托福阅读OG完整版三：DESERT FORMATION 参考译文：
沙漠已经占据了地球表面积约四分之一，而且最近几十年正以惊人的速度扩张。沙漠化是指类似沙漠的环境漫延到原本并非沙漠的区域。据估计，地球表面另外四分之一的地方正面临沙漠化威胁。沙漠化主要通过以下过程实现：首先自然植被不断减少，随后风力和雨水加速了土壤的腐蚀。有的时候松散的土壤全部被风刮走，留下石质化的表层;其它情况下细小的沙粒可能会被吹走，而正常沙粒大小的砂子不断堆积，从而形成移动的沙丘或者沙脊。
即便是在保留了土壤表层的区域，植被减少也已成为土壤大量吸取地下水的能力下降的典型因素。雨水对松散土壤的冲击会把细小的粘土颗粒冲到土壤空隙中，封闭了土壤并降低土地表层水的渗透率。地表对水的吸收急剧减少，大量水资源流失，因此土壤的腐蚀率也随即增加。地表吸收水分的能力进一步弱化使得土壤越发干燥，导致植被的进一步流失，于是便形成了土壤沙漠化的恶性循环。在一些地方，沙漠面积的扩大很大程度上归因于干燥的气候条件。在过去的几千年里，不断增加的温室效应使得一些地方干旱问题愈发严重。倘若空气污染带来的温室效应继续恶化，沙漠化进程会在未来数十年内加速实现。
然而，可以肯定的是，大部分地区沙漠化主要都是由于人类活动造成，而非自然条件导致。沙漠边缘的半干旱土地所处的生态平衡环境非常脆弱，环境压力持续增加，而这些半干旱区域适应环境压力的能力极其有限。人口数量的增加使得人们不断向土地施压，依其提供实物和燃料。在湿润的季节里，土地兴许能够应付这些压力。但是在干旱的季节里，在沙漠周边的土地上，存在着这样一个十分普遍的现象：人类对土地施加的压力远远超过了土地自身减压的能力，因此最终形成了沙漠。
导致沙漠化的主要因素有四个：过度种植，过度放牧，过分砍伐，过度灌溉。由于人口密度增加，人们对粮
食作物的种植已经扩展到日益干燥的区域进行。这些区域很有可能经常会发生干旱，所以农作物种植失败是很正常的事情。种植大量农作物需要事先移除天然植被，而农作物欠收后又会留下大面积荒地，非常容易被风力和雨水侵蚀。
在半干旱地区，草坪是主要的天然植被，家畜饲养是当地的一项主要经济活动。在一个地区过量饲养家畜会导致植被覆盖面积减少，土地被大量践踏和碾碎。通常，随之而来的就是土地硬化和加速侵蚀。
在很多国家木材是用来做饭和加热的最主要燃料。人口增加带来的压力促使人们大量砍伐木材，导致许多城市和乡村周围大面积树木和灌木减少。同时人们大量使用烘干的动物排泄物作为替代燃料同样对土壤不利，因为这些珍贵的土壤成分调节剂和植物营养资源将不会再回归至土壤当中。
造成土地沙漠化的最后一个主要人为因素在于人类过度灌溉导致土壤的盐碱化。灌溉多余的水渗透到地下水位。假如没有排水系统的存在，那么地下水位上升，把溶解的盐分带到土壤表面。水分蒸发后，盐分留在了表面，形成白色的地壳层，这一地壳层阻止了空气和水接触地底下的土壤。
沙漠化问题异常严重，这是因为有佷广阔的地区和数量庞大的人群都受到了沙漠化的影响，而且要想逆转沙漠化的进程甚至减缓沙漠化的速度都面临着巨大的困难。一旦土壤被侵蚀，需要再经过几百到上千年的时间才会产生新的土壤。那些大量土壤仍保存完好的地方，亟需一个严谨而有力的保护政策和植被覆盖计划来保护现有土地。
以上就是有关托福阅读OG第三篇的完整原文及译文，同时我们还为大家附上了完整版的相关资料供大家下载，希望你在接下来的托福阅读备考过程中合理利用以上资料，，取得高分，成功拿到名校offer。
篇二：托福OG阅读例题详解(上)
智课网TOEFL备考资料
托福OG阅读例题详解(上)
摘要： 托福OG阅读例题详解(上)。托福(TOEFL)考试中，OG既是指ETS考试中心官方给出的应试指南。虽然题型不难，但是作为官方唯一的指导型备考资料还是很重要的，以下文章为你奉上DESERT FORMATION 的试题分析，希望对你的考试有帮助：
1. threaten意思是威胁，不理解的话可以看前面一句，前面说以前不是沙漠的地方变成沙漠的过程叫做沙漠化，然后就接着说还有另外四分之一的土地面临变成沙漠的危险，B正确，A限制C阻碍D拒绝，全都错
2. 以natural vegetation定位，文章一共出现了两次，因为问题问的是结果，所以第一次出现的natural vegetation正确，原文说results in the loss of the soil's ability to absorb substantial quantities of water，B正确
3. delicate意思是脆弱的，柔软的或者精致的，原文说半干旱地区的生态环境非常怎么样，然后又说适应环境压力增加的能力非常有限，说明环境很脆弱，A正确，B可预测的C复杂的D有价值的都不沾边
4. 与上一道题是同一句话，意思与A选项重合
5. progress进展进步可得
6. raising of crops做关键词定位至最后一句话，necessitate=need，C正确
7. devoid of就是没有，前文的crop failure指的是作物绝收，所以是没有植被的土地，D正确
8. excess water做关键词定位至二三两句，说土壤过量吸水导致地下水位升高，并将盐分带到土壤表面，导致盐渍化，D正确
9. 考全文的题应关注各段的开头结尾，A,B,D答案分别在第二、四、七段有提到，第九段的内容与C相反
10. 原句的结构是desertification的严重性由两个原因导致，A选项忠实改写了原文，B把原因的一部分变成了结果，C中的only if和D中的unless都表明组成句子的短句之间的关系与原文不符，所以错
11. 以future of desertification定位，没有future但有centuries or millennia，说经过数个世纪或者数千年新的土壤才能形成，就是说没有这么久的话没法形成，那么沙化也当然会变严重了。A选项government没说，B选项说影响沙漠化的因素是周期性的没提，D选项违反常识
12. livestock重叠，economic reliance= major economic activity，overgrazing与原文grazing重叠，都说明B是正确答案
13. Growing选项对应第五段首句，正确
As periods选项虽然好像对应第四段，但crop failure没提，错
Excessive numbers选项对应第七第八两段的首句，正确
Extensive irrigation选项对应原文第九段首句，正确
Animal dung选项太细节，错
grasses选项不是第七段首句的主要内容，不选
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篇三：托福OG阅读例题详解(一)
智课网TOEFL备考资料
托福OG阅读例题详解(一)
摘要： 托福OG阅读例题详解(一)。上一篇文章呢主要从题型讲解里摘取的六道例题，接下来开始讲解六篇例文。下面这篇文章主要介绍的是THE ORIGINS OF CETACEANS的13篇文章。希望对你的托福阅读有指导性意义。
1. 以blowhole作为关键词，定位至the presence of a fluke and blowhole cannot disguise their affinities with land-dwelling mammals处，原文所说的不能掩饰古鲸类与哺乳动物的亲密关系被B选项中不能掩饰古鲸类是哺乳动物的事实同义替换，注意两个动词disguise和conceal，还有选项A中的clearly indicate和不能掩饰程度不同，所以A错
2. 以early sea otter作为关键词，定位至However, unlike the cases of sea otters and pinnipeds, it is not easy to envision what the first whales looked like. 是一种对比推断，与sea otter不同，不能预想早期的鲸长什么样，就是能预测sea otter长什么样，A正确
3. 词汇，precious意思是珍贵的，猜测方法是although limited to a skull，说明很少，转折之后是个感情色彩正向的词，只有valuable是绝对正向，其他三个A准确的，B稀少的，D开始的，大写的都完全不靠谱
4. 以Pakicetus做关键词，找到第二句skull is cetacean-like，得到答案C
5. 找前句的主语得到答案
6. expose是暴露之意，ex=out，外，pose是放置，摆放，摆在外面当然就是暴露，而且原句中found in the sediments和now exposed形成并列关系，所以visible正确，其他三个A解释C辨认D定位都不沾边。
7. 用Basilosuraus和hind leg做关键词，定位至倒数第二句和倒数第三句，得到答案D
8. 全段最后一句说Basilosaurus was undoubtedly a fully marine whale，所谓fully marine就是干嘛都在水里，所以bred and gave birth也不例外
9. 第五段开头就说这是一个很让人激动的发现，说明这个发现对研究鲸的进化有帮助。A太肤浅，没有表达作者的隐含意思;C中复原完整的骨骼没说，D太绝对，错
10. 原句的结构是backbone的结构说明Am的游泳姿势像现代鲸，Am有backbone，所以选项A说反了，backbone与fluke没有证明关系，B没说;D选项different ways与原文矛盾，错
11. propulsion指的是向前推动，pro表向前，pulse表示脉动。此外后句列举了鲸在陆地上的移动方式，从这句也能退出答案
12. 简单，待插入句说this is a question，说明正确插入点之前必须得有一个问题，只有B符合
13. Recent discoveries和fossils thought选项对应首段的首末句，正确
The discoveries选项对应第五段的最后两句，正确
The skeleton选项太细节，不选
Packicetus选项原文没有对应，而且过于绝对，不选
Am选项太细节，不选
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