7月20日托福阅读考试真题解析.doc

澳际教育旗下高端语言培训品牌好好学好好学：2013年7月20日托福阅读考试真题解析第一篇：地址对美国经济的影响讲美国的各种地质特点促进农业发展，进而促进经济发展，包括：风的作用形成平原，使金属矿物得以挖掘，冰川回退留下肥沃土地等等，最终对全世界各地的农业及经济发展产生良好影响。解析：本文属于地质学和农业话题组合，但都是托福阅读常考话题。在TPO中只有分别考察农业、地质学等内容的文章，并不话题交叉，可分别复习。Great PlainsThe northern and southern Great Plains are a broad expanse of flat land, much of it covered in prairie,steppe and grassland,which lies west of the Mississippi River and east of the Rocky Mountains in the United States and Canada.This area covers parts of the U.S. states of Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming, and the Canadian provinces of Alberta, Manitoba and Saskatchewan.The Canadian portion of the Plains is known as the Prairies. Some geographers include some territory of Mexico in the plains, but many stop at the Rio Grande. The region is known for supporting extensive ranching and agriculture.GeologyThe Great Plains are the westernmost portion of the vast North American Interior Plains, which extend east to the Appalachian Plateau. The United States Geological Survey divides the Great Plains in the United States into ten physiographic subdivisions:During the Cretaceous Period (145-65 million years ago), the Great Plains was covered by a shallow inland sea called the Western Interior Seaway. However, during the Late Cretaceous to the Paleocene (65-55 million years ago), the seaway had begun to recede, leaving behind thick marine deposits and a relatively flat terrain where the seaway had once occupied.Paleontological finds in the area have yielded bones of woolly mammoths, saber toothed tigers and other ancient animals, as well as dozens of other megafauna (large animals over 100 lb (45kg) - such as giant sloths, horses, mastodons, and American lion - that dominated the area of the ancient Great Planis for million of years. The vast majority of these animals went extinct in North America around 13,000 years ago during the end of the Pleistocene.第二篇：动物的迁徙主要讲动物如何迁徙，原因不同。先举了蝴蝶与鲸鱼的例子，表明动物靠环境信号。然后说动物还靠内部生物钟判定方向，但有的鸟不靠这个方法。最后还有一些动物靠磁场导航。解析：本文属生物学话题，考察动物迁徙。类似内容在过去的托福考试中曾多次出现，分别考察过包括蜜蜂、鸟、蚂蚁、海龟等多种动物的迁徙导航，可谓是经久不衰。本文与TPO中Orientation and Navigation一篇较为对应，可作为参考。Animal navigationAnimal navigation is the ability of many animals to find their way accurately without maps or instruments.Birds such as the Arctic tern,insects such as the monarch butterfly and fish such as the salmon regularly migrate thousands of miles to and from their breeding grounds,and many other species navigate effectively over shorter distances.Dead reckoning,navigating from a known position using only information about ones own speed and direction, was suggested by Charles Darwin in 1873 as a possible mechanism. In the 20th century, Karl von Frisch showed that honey bees can navigate by the sun, by the polarization pattern of the blue sky, and by the earths magnetic field;of these,they rely on the sun when possible.William Tinsley Keeton showed that homing pigeons could similarly make use of a range of navigational cues,including the sun,earths magnetic field,olfaction and vision. Ronald Lockley demonstrated that a species of small seabird, the Manx shearwater, could orient themselves and fly home at full speed, when released far from home,provided either the sun or the stars were visible.Several species of animal can integrate cues of different types to orient themselves and navigate effectively. Insects and birds are able to combine learned landmarks with sensed direction (from the earths magnetic field or from the sky) to identify where they are and so to navigate.Internal maps are often formed using vision, but other senses including olfaction and echolocation may also be used.The ability of wild animals to navigate may be adversely affected by products of human activity. For example,there is evidence that pesticides may interfere with bee navigation, and that lights may harm turtle navigation.How do these birds navigate at night?In the 1950s, German ornithologists Franz and Eleanore Sauer demonstarated that night flying birds have the ability to navigate by the stars. In the 1970s, Stephen Emlen took this a step further and identified the precise taer patterns that Indigo Buntings use when navigating at night.It was assumed that the North Star was important as it is fixed in the night sky, but the surprising result was that the birds instead used star patterns within about 35 degrees of the North star.Interestingly, there is little evidence that the moon plays a role in nighttime navigation by birds.In fact, the evidence seems to suggest that a birght moon actually interferes with stellar navigation.This brings us to the topic of man-made light pollution that blots out the stars across much of North America, especially around highly populate areas. What actually is the impact of light pollution on bird migration and other flora and fauna, and on man himself? We will deal with this topic in a future posting.第三篇 金星和地球的对比讲金星Venus和地球对比，金星含较多CO2。最开始金星和地球性质相似，后来因为地球较太阳更近，温度高，逐渐蒸发，造成不同。解析：本文属天文学话题，考察行星之间的对比。话题与TPO中Planets in our Solar System 一篇较为对应，可作为参考。下附金星和地球对比的相关文章。Venus compared with the EarthVenus is often named as Earths twin because both worlds share a similar size, surface composition and have an atmosphere with a complex weather system.The figure on the right compares Venus and Earth spacecraft images.The surface of Venus is shown in orange as radar images while the atmosphere is reproduced on near true colors as it would be seen by the human eye.The upper clouds are brightest in the blue and ultraviolet wavelengths making Venus a white-blue color planet. Both planets have almost the same size and density and Venus is only a 30% closer to the Sun than Earth. Both share an interesting geological evolution with old volcanoes in Venus and some of them could still be active. One of the biggest mysteries of Venus is why its surface is so young on geological time-scales. It is interesting to remark that there is almost no water on Venuss atmosphere.There are many more differences between both planets.Whereas Earth rotates in about 24 hours Venus rotates in the contrary sense (retrograde rotation) in 243 days. The orbital period of Venus is 225 days so that a Venus year takes less than a full day. The combination of these two periods results in the Sun appearing from the West and disappearing over the East with a day-night cycle of 117 days.The atmosphere of Venus is 90 times more dense than that on Earth an it is made of 96.5% of CO2 and a 3% of nitrogen. This means that both planets have the same amount of Nitrogen on their atmospheres. Surprisingly the CO2 on Earth