新托福黄金精选阅读【pdf高清下载】

1、智课网TOEFL备考资料新托福黄金精选阅读【PDF高清下载】摘要： 新托福黄金精选阅读是2015年以来托福考试界最受欢迎的资料之一，究竟新托福黄金精选阅读的亮点在哪里，下面我们就来简单了解一下，同时有需要下载的小伙伴扫描页面中的二维码即可获得。新 托福 黄金精选阅读里面的真题全部来源于ETS官网，且每一篇文章都附有详细的解析和答案，对我们备考 托福阅读 非常有用.,可以说 新托福 黄金精选阅读几乎是人手一本的精华资料。新托福黄金精选阅读：Europa is the smallest of planet Jupiters four largest moons and the second moon out from Jupiter. Until 1979, it was just another astronomy textbook statistic. Then came the close-up images obtained by the exploratory spacecraft Voyager 2, and within days, Europa was transforme

2、d-in our perception, at least-into one of the solar systems most intriguing worlds. The biggest initial surprise was the almost total lack of detail, especially from far away. Even at close range, the only visible features are thin, kinked brown lines resembling cracks in an eggshell. And this analogy is not far off the mark.The surface of Europa is almost pure water ice, but a nearly complete absence of craters indicates that Europas surface ice resembles Earths Antarctic ice cap. The eggshell

3、analogy may be quite accurate since the ice could be as little as a few kilometers thick a true shell around what is likely a subsurface liquid ocean that , in turn, encases a rocky core. The interior of Europa has been kept warm over the eons by tidal forces generated by the varying gravitational tugs of the other big moons as they wheel around Jupiter. The tides on Europa pull and relax in an endless cycle. The resulting internal heat keeps what would otherwise be ice melted almost to the surf

4、ace. The cracklike marks on Europas icy face appear to be fractures where water or slush oozes from below.Soon after Voyager 2s encounter with Jupiter in 1979, when the best images of Europa were obtained, researchers advanced the startling idea that Europas subsurface ocean might harbor life. Life processes could have begun when Jupiter was releasing a vast store of internal heat. Jupiters early heat was produced by the compression of the material forming the giant planet. Just as the Sun is fa

5、r less radiant today than the primal Sun, so the internal heat generated by Jupiter is minor compared to its former intensity. During this warm phase, some 4.6 billion years ago, Europas ocean may have been liquid right to the surface, making it a crucible for life.Both in what is now the eastern and the southwestern United States, the peoples of the Archaic era (8,000-1,000 B.C) were, in a way, already adapted to beginnings of cultivation through their intensive gathering and processing of wild

6、 plant foods. In both areas, there was a well-established ground stone tool technology, a method of pounding and grinding nuts and other plant foods, that could be adapted to newly cultivated foods. By the end of the Archaic era, people in eastern North America had domesticated certain native plants, including sunflowers; weeds called goosefoot, sumpweed, or marsh elder; and squash or gourds of some kind. These provided seeds that were important sources of carbohydrates and fat in the diet.The e

7、arliest cultivation seems to have taken place along the river valleys of the Midwest and the Southeast, with experimentation beginning as early as 7,000 years ago and domestication beginning 4,000 to 2,000 years ago. Although the term “Neolithic” is not used in North American prehistory, these were the first steps toward the same major subsistence changes that took place during the Neolithic (8,000-2,000 B.C.) period elsewhere in the world.Archaeologists debate the reasons for beginning cultivat

8、ion in the eastern part of the continent. Although population and sedentary living were increasing at the time, there is little evidence that people lacked adequate wild food resources; the newly domesticated foods supplemented a continuing mixed subsistence of hunting, fishing, and gathering wild plants, Increasing predictability of food supplies may have been a motive. It has been suggested that some early cultivation was for medicinal and ceremonial plants rather than for food. One archaeolog

9、ist has pointed out that the early domesticated plants were all weedy species that do well in open, disturbed habitats, the kind that would form around human settlements where people cut down trees, trample the ground, deposit trash, and dig holes. It has been suggested that sunflower, sumpweed, and other plants almost domesticated themselves, that is, they thrived in human disturbed habitats, so humans intensively collected them and began to control their distribution. Women in the Archaic communities were probably the main experimenters with cultivation, because ethnoarchaeological evidence tells us that women were the main collectors of plant food and had detailed knowledge of plants.杀托之路血雨腥风没有一群逗比的小伙伴如何畅游江湖， 小马 托福备考 群，就是这么适合你。Many ants forage across the countryside in large numbers and undertake mass migrations; these activities proceed because one ant lays a trail on the ground for the others to follow. As a worker ant returns home after finding a source of food, it

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