说明文
The Mystery of Yawning
According to conventional theory,yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing,through deeper breathing,the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom.Unfortunately,the few scientific investigations of yawning have failed to find any connection between how often someone yawns and how much sleep they have had or how tired they are.About the closest any research has come to supporting the tiredness theory is to confirm that adults yawn more often on weekdays than at weekends,and that school children yawn more frequently in their first year at primary school than they do in kindergarten.Another flaw of the tiredness theory is that yawning does not raise alertness or physiological activity,as the theory would predict.Volunteers were told to think about yawning while they breathed either normal air,pure oxygen,or an air mixture with an above-normal level of carbon dioxide. If the theory was correct,breathing air with extra carbon dioxide should have triggered yawning,while breathing pure oxygen should have suppressed yawning.In fact,neither condition made any difference to the frequency of yawning,which remained constant at about 24 yawns per hour.Another experiment demonstrated that physical exercise, which was sufficiently vigorous to double the rate of breathing,had no effect on the frequency of yawning.Again the implication is that yawning has little or nothing to do with oxygen.
A completely different theory holds that yawning assists in the physical development of the lungs early in life,but has no remaining biological function in adults.It has been suggested that yawning and hiccupping might serve to clear out the fetuses airways. The lungs of a fetus secrete a liquid that mixes with its mother’s amniotic fluid.Babies with congenital blockages that prevent this fluid from escaping from their lungs are sometimes born with deformed lungs.It might be that yawning helps to clear out the lungs by periodically lowering the pressure in them.According to this theory,yawning in adults is just a developmental fossil with no biological function.But,while accepting that not everything in life can be explained by Darwinian evolution,there are sound reasons for being skeptical of theories like this one,which avoid the issue of what yawning does for adults.
The empirical evidence,such as it is,suggests an altogether different function for yawning—namely,that yawning prepares us for a change in activity level.Support for this theory came from a study of yawning behavior in everyday life.Volunteers wore wrist-mounted devices that automatically recorded their physical activity for up to two weeks:the volunteers also recorded their yawns by pressing a button on the device each time they yawned.The data showed that yawning tended to occur about 15 minutes before a period of increased behavioral activity.Yawning bore no relationship to sleep patterns,however.This accords with anecdotal evidence that people often yawn in situations where they are neither tired nor bored,but are preparing for impending mental and physical activity.Such yawning is often referred to as“incongruous”because it seems out of place,at least on the tiredness view:soldiers yawning before combat, musicians yawning before performing,and athletes yawning before competing.Their yawning seems to have nothing to do with sleepiness or boredom—quite the reverse— but it does precede a change in activity level.
文章梗概
本文对打哈欠的奥秘进行了探索，首先提出了一个人们普遍接受的原因——疲劳理论，之后又通过实验反驳了这一理论的合理性。继而给出了一个与生理发育有关的理论，认为打哈欠有助于胎儿呼吸系统的发育，但这又无法解释成人打哈欠的现象。在文章的结尾，作者提出了另外一个较为靠谱的理论，至于是什么，请自己去文中找找看。
词汇
conventional[kən′vɛnʃənl]adj.符合习俗的，传统的；常见的；惯例的
investigation[ɪn，vɛstɪ′geʃən]n.调查；调查研究
trigger[′trɪgɚ]v.引发，引起；触发
vigorous[′vɪgərəs]adj.有力的；精力充沛的
empirical[ɪm′pɪrɪkl]adj.经验主义的，完全根据经验的
anecdotal[，ænɪk′dəʊt]adj.轶事的；像轶事一样的
incongruous[ɪn′kɑŋgruəs]adj.不协调的；不一致的
长难句
According to conventional theory,yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing,through deeper breathing,the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom.
根据传统理论，当人们无聊或者困倦时才会打哈欠。睡眠不足或无聊时会引起浅呼吸，打哈欠可通过抑制浅呼吸导致的血氧水平下降，达到提高人体警觉的功能。
Ancient Egyptian Sculpture
In order to understand ancient Egyptian art,it is vital to know as much as possible of the elite Egyptians’view of the world and the functions and contexts of the art produced for them.Without this knowledge we can appreciate only the formal content of Egyptian art,and we will fail to understand why it was produced or the concepts that shaped it and caused it to adopt its distinctive forms.In fact,a lack of understanding concerning the purposes of Egyptian art has often led it to be compared unfavorably with the art of other cultures:Why did the Egyptians not develop sculpture in which the body turned and twisted through space like classical Greek statuary?Why do the artists seem to get left and right confused?And why did they not discover the geometric perspective as European artists did in the Renaissance?The answer to such questions has nothing to do with a lack of skill or imagination on the part of Egyptian artists and everything to do with the purposes for which they were producing their art.
The majority of three-dimensional representations,whether standing,seated,or kneeling, exhibit what is called frontality:they face straight ahead,neither twisting nor turning.When such statues are viewed in isolation,out of their original context and without knowledge of their function,it is easy to criticize them for their rigid attitudes that remained unchanged for three thousand years.Frontality is,however,directly related to the functions of Egyptian statuary and the contexts in which the statues were set up.Statues were created not for their decorative effect but to play a primary role in the cults of the gods,the king,and the dead.They were designed to be put in places where these beings could manifest themselves in order to be the recipients of ritual actions.Thus it made sense to show the statue looking ahead at what was happening in front of it,so that the living performer of the ritual could interact with the divine or deceased recipient.Very often such statues were enclosed in rectangular shrines or wall niches whose only opening was at the front, making it natural for the statue to display frontality.Other statues were designed to be placed within an architectural setting,for instance,in front of the monumental entrance gateways to temples known as pylons,or in pillared courts,where they would be placed against or between pillars:their frontality worked perfectly within the architectural context.
Apart from statues representing deities,kings,and named members of the elite that can be called formal,there is another group of three-dimensional representations that depicts generic figures,frequently servants,from the nonelite population.The function of these is quite different.Many are made to be put in the tombs of the elite in order to serve the tomb owners in the afterlife.Unlike formal statues that are limited to static poses of standing, sitting,and kneeling,these figures depict a wide range of actions,such as grinding grain, baking bread,producing pots,and making music,and they are shown in appropriate poses,bending and squatting as they carry out their tasks.
文章梗概
理解古埃及精英阶层的世界观和当时艺术创造的背景和功用，才能真正窥探到古埃及艺术所秉持的艺术理念。文章提出了古埃及艺术单纯从审美角度审视备受诟病的原因：左右不分，眼睛永远都是直视前方，不会使用几何透视。并在其后从祭祀和摆放位置等角度给出了思考和答案。
词汇
vital[′vaɪtl]adj.至关重要的；生死攸关的
elite[ɪ′li:t]n.精英；精华
cult[kʌlt]n.祭仪（尤其指宗教上的）；礼拜
recipient[rɪ′sɪpɪənt]n.接受者；容纳者
divine[dɪ′vaɪn]adj.神圣的；非凡的；天赐的
deity[′deəti]n.神；神性
squat[skwɑt]v.蹲下；蹲坐
长难句
1.Without this knowledge we can appreciate only the formal content of Egyptian art, and we will fail to understand why it was produced or the concepts that shaped it and caused it to adopt its distinctive forms.
没有这种认识，我们只能窥探到古埃及艺术的常规内容，而不能掌握这一艺术形式形成的因由，以及采用这些独特艺术形式的原因。
2.The answer to such questions has nothing to do with a lack of skill or imagination on the part of Egyptian artists and everything to do with the purposes for which they were producing their art.
这个问题的答案与古埃及艺术家技术不精或想象力匮乏毫不相干，而恰恰体现了他们创造这些艺术的意图所在。
Ancient Rome
There is a quality of cohesiveness about the Roman world that applied neither to Greece nor perhaps to any other civilization,ancient or modern.Like the stone of Roman wall, which were held together both by the regularity of the design and by that peculiarly powerful Roman cement,the various parts of the Roman realm were bonded into a massive,monolithic entity by physical,organizational,and psychological controls.The physical bonds included the network of military garrisons,which were stationed in every province,and the network of stone-built roads that linked the provinces with Rome.The organizational bonds were based on the common principles of law and administration and on the universal army of officials who enforced common standards of conduct.The psychological controls were built on fear and punishment—on the absolute certainty that anyone or anything that threatened the authority of Rome would be utterly destroyed.
The source of Roman obsession with unity and cohesion may well have lain in the pattern of Rome’s early development.Whereas Greece had grown from scores of scattered cities, Rome grew from one single organism.While the Greek world had expanded along the Mediterranean seas lanes,the Roman world was assembled by territorial conquest.Of course,the contrast is not quite so stark:in Alexander the Great the Greeks had found the greatest territorial conqueror of all time;and the Romans,once they moved outside Italy, did not fail to learn the lessons of sea power.Yet the essential difference is undeniable. The key to the Greek world lay in its high-powered ships;the key to Roman power lay in its marching legions.The Greeks were wedded to the sea;the Romans,to the land.The Greek was a sailor at heart;the Roman,a landsman.
Certainly,in trying to explain the Roman phenomenon,one would have to place great emphasis on this almost instinct for the territorial imperative.Roman priorities lay in the organization,exploitation,and defense of their territory.In all probability it was the fertile plain of Latium,where the Latins who founded Rome originated,that created the habits and skills of landed settlement,landed property,landed economy,landed administration, and a land-based society.From this arose the Roman genius for military organization and orderly government.In turn,a deep attachment to the land,and to the stability which rural life engenders,fostered the Roman virtues:gravitas,a sense of responsibility,peitas,a sense of devotion to family and country,and iustitia,a sense of the natural order.
文章梗概
本文论述了古罗马文化的特点，其凝聚力来源于物理、组织结构和精神层面的束缚，也与其早期的发展道路、发展模式息息相关。而罗马人强烈的土地概念也孕育了罗马人的品格：责任感、对家庭和国家的牺牲精神以及对自然秩序的遵从。虽然人们对罗马文明的态度各异，有对其权力的欣赏，也有对其沿袭古希腊文化的诟病，但毋庸置疑的是文明的承袭和演进才是正常的发展轨迹。
词汇
cohesiveness[kǝʊ′hisɪvnɪs]n.凝聚力
monolithic[，mɑnǝ′lɪθɪk]adj.整体的；巨石的，庞大的
garrison[′gærəsn]n.要塞；卫戍部队
stark[stɑrk]adj.完全的；荒凉的；刻板的
imperative[ɪm′pɛrətɪv]n.需要；命令
moral[′mɔrəl]adj.道德的；精神上的；品行端正的
successor[sək′sɛsɚ]n.继承者；后续的事物
长难句
1.The organizational bonds were based on the common principles of law and administration and on the universal army of officials who enforced common standards of conduct.The psychological controls were built on fear and punishment— on the absolute certainty that anyone or anything that threatened the authority of Rome would be utterly destroyed.
组织上的羁绊则基于法律和行政的一般原则，以及遍布各地、统一行动的军政府。精神上的控制则建立在恐惧和惩罚上——毫无疑问的是任何人或任何事，只要威胁到罗马的权威，都终将被摧毁。
2.For many,Rome is at best the imitator and the continuator of Greece on a larger scale.Greek civilization had quality;Rome,mere quantity.Greece was original; Rome,derivative.Greece had style;Rome had money.Greece was the inventor; Rome,the research and development division.
对于很多人而言，罗马最多不过是对希腊更大规模的模仿和延续，希腊文明拥有质量，罗马则仅仅拥有数量。希腊是发明者，而罗马则是研究和发展的分支。
The Origins of Agriculture
How did it come about that farming developed independently in a number of world centers(the Southeast Asian mainland,Southwest Asia,Central America,lowland and highland South America,and equatorial Africa)at more or less the same time?Agriculture developed slowly among populations that had an extensive knowledge of plants and animals.Changing from hunting and gathering to agriculture had no immediate advantages.To start with,it forced the population to abandon the nomad’s life and become sedentary,to develop methods of storage and,often,systems of irrigation.While hunter-gatherers always had the option of moving elsewhere when the resources were exhausted,this became more difficult with farming.Furthermore,as the archaeological record shows,the state of health of agriculturalists was worse than that of their contemporary hunter-gatherers.
Traditionally,it was believed that the transition to agriculture was the result of a worldwide population crisis.It was argued that once hunter-gatherers had occupied the whole world, the population started to grow everywhere and food became scarce;agriculture would have been a solution to this problem.We know,however,that contemporary hunter-gatherer societies control their population in a variety of ways.The idea of a world population crisis is therefore unlikely,although population pressure might have arisen in some areas.
Climatic changes at the end of the glacial period 13,000 years ago have been proposed to account for the emergence of farming.The temperature increased dramatically in a short period of time(years rather than centuries),allowing for a growth of the hunting-gathering population due to the abundance of resources.There were,however,fluctuations in the climatic conditions,with the consequences that wet conditions were followed by dry ones, so that the availability of plants and animals oscillated brusquely.
It would appear that the instability of the climatic conditions led populations that had originally been nomadic to settle down and develop a sedentary style of life,which led in turn to population growth and to the need to increase the amount of food available. Farming originated in these conditions.Later on,it became very difficult to change because of the significant expansion of these populations.It could be argued,however,that these conditions are not sufficient to explain the origins of agriculture.Earth had experienced previous periods of climatic change,and yet agriculture had not been developed.
It is archaeologist Steven Mithen’s thesis,brilliantly developed in his book The Prehistory of the Mind(1996),that approximately 40,000 years ago the human mind developed cognitive fluidity,that is,the integration of the specializations of the mind:technical,natural history(geared to understanding the behavior and distribution of natural resources),social intelligence,and the linguistic capacity.Cognitive fluidity explains the appearance of art, religion,and sophisticated speech.Once humans possessed such a mind,they were able to find an imaginative solution to a situation of severe economic crisis such as the farming dilemma described earlier.Mithen proposes the existence of four mental elements to account for the emergence of farming:(1)the ability to develop tools that could be used intensively to harvest and process plant resources;(2)the tendency to use plants and animals as the medium to acquire social prestige and power;(3)the tendency to develop “social relationships”with animals structurally similar to those developed with people— specifically,the ability to think of animals as people(anthropomorphism)and of people as animals(totemism);and(4)the tendency to manipulate plants and animals. The fact that some societies domesticated animals and plants,discovered the use of metal tools,became literate,and developed a state should not make us forget that others developed pastoralism or horticulture(vegetable gardening)but remained illiterate and at low levels of productivity;a few entered the modern period as hunting and gathering societies.It is anthropologically important to inquire into the conditions that made some societies adopt agriculture while others remained hunter-gatherers or horticulturalists. However,it should be kept in mind that many societies that knew of agriculture more or less consciously avoided it.Whether Mithen’s explanation is satisfactory is open to contention,and some authors have recently emphasized the importance of other factors.
文章梗概
本文开门见山地探讨了农业的起源问题，并提出了几个不同的看法，从传统上广为接受的人口危机导致的结果，到冰河世纪末期气候的转变，再到科学家斯蒂文·米森从人类认知领域提出的解释，并对这3种解释做出分析。
词汇
agriculturalist[，ægrɪ′kʌltʃǝrǝlɪst]n.农学家；农民
irrigation[，ɪrɪ′geʃn]n.灌溉
archaeology[，ɑrkɪ′ɑlǝdʒi]n.考古学
consequence[′kɑnsǝkwɛns]n.结果；重要性；推论
scarce[skɛrs]adj.缺乏的，不足的；稀有的
prestige[prɛ′stidʒ]n.威望，声望；声誉
illiterate[ɪ′lɪtǝrǝt]adj.文盲的；不识字的
horticulturalist[，hɒtɪ′kʌltʃǝrǝlɪst]n.园艺种植者
contention[kǝn′tɛnʃǝn]n.争论，争辩；争夺
长难句
1.It would appear that the instability of the climatic conditions led populations that had originally been nomadic to settle down and develop a sedentary style of life,which led in turn to population growth and to the need to increase the amount of food available.
似乎是气候条件的不稳定性造成了那些原本放牧的人定居下来，逐渐发展出了定居的生活方式，这也反过来造成人口增长以及所需实物数量的增加。
2.It is anthropologically important to inquire into the conditions that made some societies adopt agriculture while others remained hunter-gatherers or horticulturalists. However,it should be kept in mind that many societies that knew of agriculture more or less consciously avoided it.探究使某种社会选择农业而其他社会停留在狩猎采集或园艺的条件具有重要的考古学意义。但是我们应该记住，有很多知晓农业的社会几乎是有意不选择它的。
The Origins of Cetaceans
It should be obvious that cetaceans—whales,porpoises,and dolphins—are mammals. They breathe through lungs,not through gills,and give birth to live young.Their streamlined bodies,the absence of hind legs,and the presence of a fluke and blowhole cannot disguise their affinities with land dwelling mammals.However,unlike the cases of sea otters and pinnipeds,it is not easy to envision what the first whales looked like.Extinct but already fully marine cetaceans are known from the fossil record.How was the gap between a walking mammal and a swimming whale bridged?Missing until recently were fossils clearly intermediate,or transitional,between land mammals and cetaceans.
Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans.In 1979,a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale.The fossil was officially named Pakicetusin honor of the country where the discovery was made.Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old.The river that formed these deposits was actually not far from an ancient ocean known as the Tethys Sea.
Another major discovery was made in Egypt in 1989.Several skeletons of another early whale,Basilosaurus,were found in sediments left by the Tethys Sea and now exposed in the Sahara desert.This whale lived around 40 million years ago,12 million years after Pakicetus.Many incomplete skeletons were found but they included,for the first time in an archaeocyte,a complete hind leg that features a foot with three tiny toes. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional,or vestigial,hind legs.
An even more exciting find was reported in 1994,also from Pakistan.The now extinct whale Ambulocetus natans(“the walking whale that swam”)lived in the Tethys Sea 49 million years ago.It lived around 3 million years after Pakicetus but 9 million before Basilosaurus.The fossil luckily includes a good portion of the hind legs.The legs were strong and ended in long feet very much like those of a modern pinniped.The legs were certainly functional both on land and at sea.The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans.The structure of the backbone shows,however,that Ambulocetus swam like modern whales by moving the rear portion of its body up and down,even though a fluke was missing.
文章梗概
本文主要介绍的是鲸鱼的起源。首段一开始引出一个众所周知的观点：鲸鱼是哺乳动物。但是这一显而易见的事情证明起来却并非易事，因为要研究最初鲸鱼的样子以及展示陆生哺乳动物与鲸鱼之间的共同点只有通过分析化石的方式。接下来通过纵向研究，作者分别指出在1979、1989、1994年的几项调查中都发现鲸鱼从陆生海洋哺乳动物向海洋哺乳动物的过渡，而这一研究过程不仅说明了鲸鱼的起源，而且进一步证明鲸鱼是连接着陆地生命和海洋生命的物种。对研究鲸鱼来说是极具重要性的3次发现。1979年，在巴基斯坦北部发掘到最古老的鲸鱼化石，通过对其头盖骨等其他身体结构的
分析，表明它们是已灭绝的食肉哺乳动物（中兽科动物）和鲸类动物的过渡型。1989年，在埃及古地中海残留的沉积物中发现了另一类早期鲸鱼Basilosaurus的一些骨骸，通过对其后肢的研究发现其形状已经非常小，并且完全退化，这些足以证明Basilosaurus是完全水生的鲸鱼。
1994年，巴基斯坦报道了一则更令人兴奋的发现，鲸鱼Ambulocetus natans（可以步行的鲸类）在4900万年前曾在古地中海生活过，其后肢很强壮，底部有长足，这些后肢使得他们既能在陆地行走又能在海里游行。
词汇
cetacean[sɪ′teɪʃn]n.鲸鱼；鲸类动物
porpoise[′pɔ:pəs;′pɒpɒɪs]n.海豚；鼠海豚
gill[gɪl]n.腮
affinity[ə′fɪnɪtɪ]n.密切关系；吸引力
archaeocyte[ɑ:′ki:əsɪt]n.原细胞
vestigial[ve′stɪdʒɪəl;-dʒ(ə)l]adj.退化的；残余的；发育不全的
pinniped[′pɪnɪped]adj.鳍足类的
jawbone[′dʒɔ:bəʊn]n.颚骨
blowhole[′bləʊhəʊl]n.（鲸、海豚等的）喷水孔
sediment[′sedɪm(ə)nt]n.沉积；沉淀物
propulsion[prə′pʌlʃ(ə)n]n.推进；推进力
locomotion[ləʊkə′məʊʃ(ə)n]n.运动；移动；旅行
长难句
The structure of the backbone shows,however,that Ambulocetus swam like modern whales by moving the rear portion of its body up and down,even though a fluke was missing.
不过，从Ambulocetus的脊椎结构上可以看出，即使缺少尾片，它们也能像现代鲸鱼那样通过身体背部的上下摆动来游走。
Desert Formation
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.
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.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.
文章梗概
本文主要向我们普及了沙漠是怎样形成的。作者通过两方面来讲沙漠化的成因，分别是自然条件与人为因素。
沙漠化主要通过以下过程实现：首先是自然植被不断减少，随后是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；其他情况下，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，从而形成了移动的沙丘或沙脊。因此在一些地方，沙漠面积的扩大在很大程度上归因于干燥的气候条件。然而，可以肯定的是，大部分地区的沙漠化主要是由于人类活动造成的，而非自然条件所致。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。具体来讲，导致沙漠化的主要因素有4个：过度种植、过度放牧、过分砍伐、过度灌溉。大量农作物的种植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；一些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，随之而来的便是土地硬化和加速侵蚀；以及过度砍伐对土壤的破坏；再加上过度灌溉导致的土壤盐碱化，上述这些便构成了沙漠化愈演愈烈的关键因素。文章的最后，作者顺理成章地呼吁应该有相关政策以及得力的保护措施来改善这一情况。
词汇
ridge[rɪdʒ]n.山脊；山脉
clay[kleɪ]n.[土壤]粘土；泥土
penetration[penɪ′treɪʃ(ə)n]n.渗透；突破；侵入；洞察力
deterioration[dɪ，tɪərɪə′reɪʃn]n.恶化；退化；堕落
aridity[ə′rɪdətɪ]n.干旱；乏味
semiarid[，sem(a)ɪ′ærɪd]adj.半干旱的；雨量非常少的
overgraze[，əʊɚ′ɡrez]vi.过度放牧
overirrigation[əʊvərɪrɪ′ɡeɪʃn]n.过量灌溉
tract[trækt]n.束；大片土地，地带
pulverization[，pʌlvərɪ′zeʃən]n.粉碎；研碎；彻底摧毁
trample[′træmp(ə)l]vt.践踏；蔑视，伤害
shrub[ʃrʌb]n.灌木；灌木丛
长难句
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.
大多数农作物的种植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。
Early Cinema
The cinema did not emerge as a form of mass consumption until its technology evolved from the initial“peepshow”format to the point where images were projected on a screen in a darkened theater.In the peepshow format,a film was viewed through a small opening in a machine that was created for that purpose.Thomas Edison’s peepshow device,the Kinetoscope,was introduced to the public in 1894.It was designed for use in Kinetoscope parlors,or arcades,which contained only a few individual machines and permitted only one customer to view a short,50-foot film at any one time.
These Kinetoscope arcades were modeled on phonograph parlors,which had proven successful for Edison several years earlier.In the phonograph parlors,customers listened to recordings through individual ear tubes,moving from one machine to the next to hear different recorded speeches or pieces of music.The Kinetoscope parlors functioned in a similar way.
With the advent of projection in 1895-1896,motion pictures became the ultimate form of mass consumption.Previously,large audiences had viewed spectacles at the theater, where vaudeville,popular dramas,musical and minstrel shows,classical plays,lectures, and slide-and-lantern shows had been presented to several hundred spectators at a time.But the movies differed significantly from these other forms of entertainment,which depended on either live performance or(in the case of the slide-and-lantern shows)the active involvement of a master of ceremonies who assembled the final program.
Although early exhibitors regularly accompanied movies with live acts,the substance of the movies themselves is mass-produced,prerecorded material that can easily be reproduced by theaters with little or no active participation by the exhibitor.Even though early exhibitors shaped their film programs by mixing films and other entertainments together in whichever way they thought would be most attractive to audiences or by accompanying them with lectures,their creative control remained limited.What audiences came to see was the technological marvel of the movies;the lifelike reproduction of the commonplace motion of trains,of waves striking the shore,and of people walking in the street;and the magic made possible by trick photography and the manipulation of the camera.
文章梗概
本文主要讲的是电影院的播放技术从最初的西洋镜形式演变为将影像投影到幽暗的影院屏幕，这一转变使得电影院大众化消费成为可能这一事情。文章主要是从历史的角度来讲电影放映技术的发展进程，同时也提到了电影放映方式的转变，从电影伴有现场表演到表演慢慢减少，最终实现了电影消费群的扩大化。
在通过西洋镜播放电影的年代里，人们只能通过播放仪器的一个专门设置的小窗口来看电影。之后，托马斯·爱迪生发明的活动电影放映机公布于众，这种放映机仅适用于活动电影放映室或电影娱乐城。这些电影播放厅是仿照留声机播放厅设计的，随后电影放映者们期望将自己的收益最大化，他们希望能更简易地将少量电影同时放映给几百个顾客（而不是每次为一个顾客播放一次电影），于是开始有了正当的影院等多人观影场所。伴随着投影机的到来，电影不再属于少数人的消费品。
词汇
peepshow[′pi:pʃəu]n.西洋镜
Kinetoscope[kɪ′nitəskop]n.活动电影放映机；活动照相机；投观影装置
arcade[ɑ:′keɪd]n.拱廊；
parlor[′pɑrlɚ]n.客厅；会客室；业务室
prizefight[′praɪzfaɪt]n.职业拳击赛；徒手拳vaudeville[′vɔ:dəvɪl;′vəʊd-]n.杂耍；轻歌舞剧；
歌舞杂耍表演makeshift[′meɪkʃɪft]adj.临时的；权宜之计的；
凑合的fairground[′feəgraʊnd]n.露天市场；举行赛会
的场所；游乐场
长难句
But the movies differed significantly from these other forms of entertainment,which depended on either live performance or(in the case of the slide-and-lantern shows) the active involvement of a master of ceremonies who assembled the final program.
向电影与这些娱乐形式明显的不同点是，电影无需依赖现场表演，也不需要串联全场节目的主持人的积极参与（例如胶片演示）。
Aggression
When one animal attacks another,it engages in the most obvious example of aggressive behavior.Psychologists have adopted several approaches to understanding aggressive behavior in people.
The Biological Approach.Numerous biological structures and chemicals appear to be involved in aggression.One is the hypothalamus,a region of the brain.In response to certain stimuli,many animals show instinctive aggressive reactions.The hypothalamus appears to be involved in this inborn reaction pattern:electrical stimulation of part of the hypothalamus triggers stereotypical aggressive behaviors in many animals.In people, however,whose brains are more complex,other brain structures apparently moderate possible instincts.
The sociobiology view has been attacked on numerous grounds.One is that people’s capacity to outwit other species,not their aggressiveness,appears to be the dominant factor in human survival.Another is that there is too much variation among people to believe that they are dominated by,or at the mercy of,aggressive impulses.
The Psychodynamic Approach.Theorists adopting the psychodynamic approach hold that inner conflicts are crucial for understanding human behavior,including aggression. Sigmund Freud,for example,believed that aggressive impulses are inevitable reactions to the frustrations of daily life.Children normally desire to vent aggressive impulses on other people,including their parents,because even the most attentive parents cannot gratify all of their demands immediately.Yet children,also fearing their parents’punishment and the loss of parental love,come to repress most aggressive impulses.The Freudian perspective,in a sense:sees us as“steam engines.”By holding in rather than venting “steam,”we set the stage for future explosions.Pent-up aggressive impulses demand outlets.They may be expressed toward parents in indirect ways such as destroying furniture,or they may be expressed toward strangers later in life.
The Cognitive Approach.Cognitive psychologists assert that our behavior is influenced by our values,by the ways in which we interpret our situations and by choice.For example, people who believe that aggression is necessary and justified-as during wartime-are likely to act aggressively,whereas people who believe that a particular war or act of aggression is unjust,or who think that aggression is never justified,are less likely to behave aggressively.
文章梗概
这是一篇讲述人类侵略性行为的文章。作者主要通过3种方法做了具体的分析：第一种是生物学方法，认为人的侵略性行为与许多生物结构与化学物质有关，特别是人的大脑结构这一诱因导致了人们有时会做出过激的行为；但是，该理论在众多方面遭到质疑。其一，人类拥有其他物种不具备的能力，这种并非侵略性质的能力才是人类生存下来的主要原因。其二，人类身上存在太多的变数，因此，我们无法相信人类会被侵略性冲动主导或者支配。
第二种是精神动力学方法，从研究人发出侵略性行为的动机出发，指出人经常在遭受挫败后会以此来发泄感情。
第三种是认知方法，主要介绍了影响侵略性行为的几个因素，如：价值观、解析自己处境的方式以及不同的选择等。
词汇
hypothalamus[，haɪpə(ʊ)′θæləməs]n.[解剖]下丘脑
trigger[′trɪgə]vt.引发，引起；触发
stereotypical[，steriə′tipikl]adj.老一套的；陈规的
offshoot[′ɒfʃu:t]n.分支；支流；衍生物
outwit[aʊt′wɪt]vt.瞒骗；以智取胜
vent[vent]vt.发泄感情；放出
pent-up[′pent′ʌp]adj.被压抑的；幽闭的
catharsis[kə′θɑ:sɪs]n.[医]导泻；精神发泄
valve[vælv]n.阀；活门
长难句
For example,people who believe that aggression is necessary and justified-as during wartime-are likely to act aggressively,whereas people who believe that a particular war or act of aggression is unjust,or who think that aggression is never justified,are less likely to behave aggressively.
例如，那些认为侵略性行为是必要的，并且认为战争时期侵略行为是正义的人，他们的好斗性可能更高，而认为某些战争或侵略行为是不公平的，并且认为侵略永远是不正当的人，他们遇事时不大可能会采取侵略性行为。