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新托福阅读真题机经还原(第二期)

2012-03-01 15:01 作者: 来源: 本站 浏览: 1,433 views 我要评论 字号:

摘要: 不少童鞋都在用机经备考托福,应该说机经对于备考口语和写作是有一定作用的,但对于阅读和听力来说却显得有点鸡肋了。不过要想利用机经备考阅读并非不可能,老郑博客“新托福阅读真题机经还原”系列,力争在机经的基础上还原跟真题话题一样,难度接近,语言相似的文章,供各位童鞋...

不少童鞋都在用机经备考托福,应该说机经对于备考口语和写作是有一定作用的,但对于阅读和听力来说却显得有点鸡肋了。不过要想利用机经备考阅读并非不可能,老郑博客“新托福阅读真题机经还原”系列,力争在机经的基础上还原跟真题话题一样,难度接近,语言相似的文章,供各位童鞋参考。今天是第二期 3月考试重点机经101211NA中的3篇阅读文章。

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Animal Play

 

At only three weeks of age, Dogs has already begun gnawing, pawing, and tugging at its siblings. At four to five weeks, their behaviors rival those of a mischievous child, chasing and wrestling with its siblings at all hours of the day and night.

Such behavior is not unusual among social mammals. From human children to whales to sewer rats, many groups of mammals and even some birds play for a significant fraction of their youth. Brown bear cubs, like puppies and kittens, stalk and wrestle with one another in imaginary battles. Deer play tag, chasing and fleeing from one another. Wolves play solitary games with rocks and sticks. Chimpanzees tickle one another.

However fascinating these displays of youthful exuberance may be, play among animals was ignored by scientists for most of this century. Biologists assumed that this seemingly purposeless activity had little effect on animal development, was not a distinct form of behavior, and was too implicit a concept either to define or to study. 20 Even the term “play” caused problems for researchers, because it suggests that watching animals goof off is not an activity for serious scientists.

But a steady accumulation of evidence over the past two decades now suggests that play is a distinct form of behavior with an important role in the social, physical, and mental development of many animals. In one study, kittens, mice, and rats were found to play the most at ages when permanent changes were occurring in their muscle fiber and the parts of their brains regulating movement. Kittens were most playful between 4 and 20 weeks of age; rats, from 12 to 50 days; and mice, from 15 to 29 days. Development at those ages is comparable to that of a two-year-old human infant. At these precise times in the development of these animals, muscle fibers differentiate and the connections to areas of the brain regulating movement are made. Such changes apparently are not unique to kittens, mice, and rats, but apply to mammals in general.

Thus, research on play has given biologists an important tool with which to probe the development of the brain and motor systems of animals. The study on rats, kittens, and mice may, for instance, provide a physiological explanation for why infant animals employ in their play the same kinds of behavior that they will later use as adults. By stalking and capturing imaginary prey over and over again, a kitten builds its muscle and brain connections in a way that allows it to perform those actions later in life.

Play may also provide insight into the social development of animals. When the rough-and-tumble of play ends physical damage, young animals may be learning the limits of their strength and how to control themselves among others. Those are essential lessons for an animal living in a close-knit group. Perhaps, some scientists guess, as mammals gathered into social groups, play took on the function of socializing members of the group. Not everyone agrees with this theory, though. Another explanation is that play may not have evolved to confer any advantage but is simply a consequence of higher cognitive abilities or an abundance of nutrition and parental care.

 

 

Gradualism and Punctuated Equilibrium

Gradualism and punctuated equilibrium are two ways in which the evolution of a species can occur. A species can evolve by only one of these, or by both. Scientists think that species with a shorter evolution evolved mostly by punctuated equilibrium, and those with a longer evolution evolved mostly by gradualism.

 

Gradualism is selection and variation that happens more gradually. Over a short period of time it is hard to notice. Small variations that fit an organism slightly better to its environment are selected for: a few more individuals with more of the helpful trait survive, and a few more with less of the helpful trait die. Very gradually, over a long time, the population changes. Change is slow, constant, and consistent.

In punctuated equilibrium, however, change comes in spurts. There is a period of very little change, and then one or a few huge changes occur, often through mutations in the genes of a few individuals. Mutations are random changes in the DNA that are not inherited from the previous generation, but are passed on to generations that follow. Though mutations are often harmful, the mutations that result in punctuated equilibrium are very helpful to the individuals in their environments. Because these mutations are so different and so helpful to the survival of those that have them, the proportion of individuals in the population who have the mutation and those who don’t changes a lot over a very short period of time. The species changes very rapidly over a few generations, then settles down again to a period of little change.

When Charles Darwin proposed his theory in the mid-19th century, he was confident that fossil discoveries would provide clear and convincing evidence that his conjectures were correct. His theory predicted that countless transitional forms must have existed, all gradually blending almost imperceptibly from one tiny step to the next, as species progressively evolved to higher, better-adapted forms.

However, even Darwin himself struggled with the fact that the fossil record failed to support his conclusions. “Why,” he asked, “if species have descended from other species by fine gradations, do we not everywhere see innumerable transitional forms? . . . Why do we not find them imbedded in countless numbers in the crust of the earth?” “The number of intermediate varieties, which have formerly existed, must be truly enormous,” he wrote. “Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and serious objection which can be urged against the theory”

 

The idea of punctuated equilibrium originated long after the idea of gradualism. Scientists were studying fossils and they found that some species have their evolution almost “mapped out” in fossils. For others they found a few, very different species along the evolutionary course, but very few or no fossils of “in between” organisms. Also, when dating the fossils, scientists saw that in some species change was very slow, but in others, it must have occurred rapidly to be able to produce such change over such a short amount of time. The scientists reasoned that there had to be another way that evolution could have happened that was quicker and had fewer intermediate species, so the idea of punctuated equilibrium was formed.

 

Early History of Mechanical Clock

The mechanical clock is a banality so commonplace that we take it for granted. Yet Lewis Mumford quite correctly called it the key-machine. Before the invention of this machine, people told time by sun shadow sticks or dials and water clocks. We do not know who invented this machine or where. Sun clocks worked of course only on clear days; water clocks misbehaved when the temperature fell toward freezing, to say nothing of long-run drift as a result of sedimentation and clogging. Both of these devices served reasonably well in sunny climes; but north of the Alps one can go weeks without seeing the sun, while temperatures vary not only seasonally but from day of night.

Medieval Europe gave new importance to reliable time. The Church first, with its seven daily prayer offices, one of which, matins, was in spite of its name a nocturnal rite and required an alarm  arrangement to wake clerics before dawn. And then the new cities and towns had their temporal servitudes. Squeezed by their walls, they had to know and order time in order to organize collective activity and ration space. They set a time to wake, to go to work, to open the market, close the market, leave work, and finally a time to put out fires and go to sleep.

 

All of this was compatible with the older devices so long as there was only one authoritative timekeeper; but with urban growth and the multiplication of time signals, discrepancy brought discord and strife. Society needed a more dependable instrument of time measurement and found it in the mechanical clock.

 

We do not know who invented this machine or where. It seems to have appeared in Italy and England (perhaps simultaneous invention) in the last quarter of the thirteenth century. Once known, it spread rapidly, driving out the water clocks; but not solar dials, which were needed to check the new machines against the timekeeper of last resort. These early versions were rudimentary, inaccurate, and prone to breakdown— so much so that it paid to buy a clockmaker along with the clock.

Ironically, the new machine tended to undermine ecclesiastical authority. Although Church ritual had sustained an interest in timekeeping throughout the centuries of urban collapse that followed the fall of Rome, Church time was nature’s time. Day and night were divided into the same number of parts, so that except at the equinoxes, day and night hours were unequal; and then of course the length of these hours varied with the seasons. But the mechanical clock kept equal hours, and this implied a new time reckoning. The Church resisted, not coming over to the new hours for about a century. From the start, however, the towns and cities took equal hours as their standard, and the public clocks installed in the towers of town halls and market squares became the very symbol of a new, secular municipal authority. Every town wanted one; conquerors seized them as specially precious spoils of war; tourists came to see and hear these machines the way they made pilgrimages to sacred relics.

 

The clock was the greatest achievement of medieval mechanical ingenuity. Revolutionary in conception, it was more radically new than its makers knew. This was the first example of a digital as opposed to an analog device: it counted a regular, repeating sequence of discrete actions (the swings of an oscillating controller) rather than tracked continuous, regular motion such as the moving shadow of a sundial or the flow of water. Today we know that such a repeating frequency can be more regular than any continuous phenomenon, and just about all high-precision devices are now based on the digital principle. But no one could have known that in the thirteenth century, which thought that because time was continuous, it ought to be tracked and measured by some other continuity.

 

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