托福机经：2012年9月16日托福阅读考题回顾2
小编推荐：2012年托福考试用书、考试教材
| Passage 2 | |
| Title: | 大气变化 |
| 大致内容 | 说是在最早的时候大气里有很多轻元素，比如氢和氦这类的，但是轻的东西比较容易达到逃逸速度然后飞走。 最早的时候地球的引力不够，然后为了理解这个，给了个highlight（有题），题目是说molecule会不断地push, 然后渐渐地就diffusion, 所以几乎atmosphere就不剩下什么了，除非BLABLA可以counter掉这个力。 之后就研究了在这个最早的大气消失之后的一种大气，是由火山喷发出来的水汽和comet of frozen water什么的带出来的gases, 然后这里面含有大量的vapor和CO2。 接着就讨论了CO2是怎么没有的，因为现在的大气里这两个都不是主要的了，说是有三个原因导致了CO2的消失：1是降雨，2是某种生物的光合作用导致CO2变O2了，3是会变成某种骨骼物质沉降到海底之类的（有个EXCEPT题）。 最后一段是说氮气，说氮气消失的速度非常慢（有题，问前面说CO2消失的两段和这一段能推论出什么）。 |
| 扩展阅读 | TPO23-1 Urban Climates The city is an extraordinary processor of mass and energy and has its own metabolism. A daily input of water, food, and energy of various kinds is matched by an output of sewage, solid waste, air pollutants, energy, and materials that have been transformed in some way. The quantities involved are enormous. Many aspects of this energy use affect the atmosphere of a city, particularly in the production of heat. In winter the heat produced by a city can equal or surpass the amount of heat available from the Sun. All the heat that warms a building eventually transfers to the surrounding air, a process that is quickest where houses are poorly insulated. But an automobile produces enough heat to warm an average house in winter, and if a house were perfectly insulated, one adult could also produce more than enough heat to warm it. Therefore, even without any industrial production of heat, an urban area tends to be warmer than the countryside that surrounds it. The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflections among the numerous vertical surfaces that buildings present and (2) by the dust dome the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of the dome and reradiated back to the urban surface. Cities, then, are warmer than the surrounding rural areas, and together they produce a phenomenon known as the urban heat island. Heat islands develop best under particular conditions associated with light winds, but they can form almost any time. The precise configuration of a heat island depends on several factors. For example, the wind can make a heat island stretch in the direction it blows. When a heat island is well developed, variations can be extreme; in winter, busy streets in cities can be 17℃ warmer than the side streets. Areas near traffic lights can be similarly warmer than the areas between them because of the effect of cars standing in traffic instead of moving. The maximum differences in temperature between neighboring urban and rural environments is called the heat-island intensity for that region. In general, the larger the city, the greater its heat-island intensity. The actual level if intensity depends on such factors as the physical layout population density, and productive activities of a metropolis. The surface-atmosphere relationships inside metropolitan areas produce a number of climatic peculiarities. For one thing, the presence or absence of moisture is affected by the special qualities of the urban surface. With much of the built-up landscape impenetrable by water, even gentle rain runs off almost immediately from rooftops, streets, and parking lots. Thus, city surfaces, as well as the air above them, tend to be drier between episodes of rain; with little water available for the cooling process of evaporation, relative humidities are usually lower. Wind movements are also modified in cities because buildings increase the friction on air flowing around them. This friction tends to slow the speed of winds, making them far less efficient at dispersing on airflow. Rainfall is also increased in cities. The cause appears to be in part greater turbulence in the urban atmosphere as hot air rises from the built-up surface. TPO10-1 Variations in the Climate One of the most difficult aspects of deciding whether current climatic events reveal evidence of the impact of human activities is that it is hard to get a measure of what constitutes the natural variability of the climate. We know that over the past millennia the climate has undergone major changes without any significant human intervention. We also know that the global climate system is immensely complicated and that everything is in some way connected, and so the system is capable of fluctuating in unexpected ways. We need therefore to know how much the climate can vary of its own accord in order to interpret with confidence the extent to which recent changes are natural as opposed to being the result of human activities. Instrumental records do not go back far enough to provide us with reliable measurements of global climatic variability on timescales longer than a century. What we do know is that as we include longer time intervals, the record shows increasing evidence of slow swings in climate between different regimes. To build up a better picture of fluctuations appreciably further back in time requires us to use proxy records. Over long periods of time, substances whose physical and chemical properties change with the ambient climate at the time can be deposited in a systematic way to provide a continuous record of changes in those properties overtime, sometimes for hundreds or thousands of years. Generally, the layering occurs on an annual basis, hence the observed changes in the records can be dated. Information on temperature, rainfall, and other aspects of the climate that can be inferred from the systematic changes in properties is usually referred to as proxy data. Proxy temperature records have been reconstructed from ice core drilled out of the central Greenland ice cap, calcite shells embedded in layered lake sediments in Western Europe, ocean floor sediment cores from the tropical Atlantic Ocean, ice cores from Peruvian glaciers, and ice cores from eastern Antarctica. While these records provide broadly consistent indications that temperature variations can occur on a global scale, there are nonetheless some intriguing differences, which suggest that the pattern of temperature variations in regional climates can also differ significantly from each other. What the proxy records make abundantly clear is that there have been significant natural changes in the climate over timescales longer than a few thousand years. Equally striking, however, is the relative stability of the climate in the past 10,000 years (the Holocene period). To the extent that the coverage of the global climate from these records can provide a measure of its true variability, it should at least indicate how all the natural causes of climate change have combined. These include the chaotic fluctuations of the atmosphere, the slower but equally erratic behavior of the oceans, changes in the land surfaces, and the extent of ice and snow. Also included will be any variations that have arisen from volcanic activity, solar activity, and, possibly, human activities. One way to estimate how all the various processes leading to climate variability will combine is by using computer models of the global climate. They can do only so much to represent the full complexity of the global climate and hence may give only limited information about natural variability. Studies suggest that to date the variability in computer simulations is considerably smaller than in data obtained from the proxy records. In addition to the internal variability of the global climate system itself, there is the added factor of external influences, such as volcanoes and solar activity .There is a growing body of opinion that both these physical variations have a measurable impact on the climate. Thus we need to be able to include these in our deliberations. Some current analyses conclude that volcanoes and solar activity explain quite a considerable amount of the observed variability in the period from the seventeenth to the early twentieth century’s, but that they cannot be invoked to explain the rapid warming in recent decades. |
| Passage 3 | |
| Title: | 蝙蝠的觅食习惯 |
| 大致内容 | 蝙蝠吃很多很多东西，热带的蝙蝠吃的东西种类比温带的多很多，（有题，答案就是这一句的同意改写）。 第二段开始讲各种diet的区别。 主要觅食：insect (or small animals), nectar, pollen, plant 说是insect提供了balanced diet（有题，问哪个提供最complete的营养，我选的insect, 因为其他几个讲到的时候有括弧说less protein than blabla）。 然后说到了echolocation的能力。一种蝙蝠有这种能力，可以捕捉到insect, 有protein摄入。但是另一种没有这种能力，就只吃plant。 但它也有办法补充protein, 因为在digestive tract里可以分泌特殊的enzyme来扩大能吸收的protein的量，也就够它用了。接着说到了这些蝙蝠觅食和自己的体积是很有关系的，小的就吃nectar pollen plant这类，大的会吃鱼、鸟、BLABLA。 最后说蝙蝠的常见觅食地和它的diet也有很大的关系，在水边的就会吃很多水生昆虫，飞很高的不会吃scorpion, 但是会吃飞在网上的蜘蛛。 |
| 点评： 本次新托福考试完全重复2011.08.20北美考题。 词汇题：augment, intricate, supplement, profound, tolerate, exceed, compose, constitute, account for, predominantly等。 | |
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