本文的2016年10月28日
2016年10月28日托福阅读真题词汇题：
1.coalesced=joined
2.simultaneously=at the same time
3.dismissed=rejected
4.emit=release
5.extreme=great
6.consult=ask
7.upon reflection=after consideration
8.constant=continued
9.retain=preserve
10.recognize=accept
11.elevated=high
2016年10月28日托福阅读真题第一篇 Features of Tropical Mammals(生命类)【20150712】旧题
原文回顾：整篇文章介绍了热带的哺乳动物的生活习性和特点。文章对温带和热带的哺乳动物进行对比，分析其区别。热带的哺乳动物不需要忍受极端的温度，只有经历了干湿季。在干季，由于吃的少，不能像温带动物一样，通过冬眠来度过食物短缺的季节。不能冬眠有三个原因，第一如果冬眠会被蛇吃掉，其次会收到军蚁的危险，第三就是食物。
后面讲的是热带动物和其他动物的不同。热带动物生活在热带，有高大茂密的树木。所以说，有更多的树栖动物。然后举了美国地区的蝙蝠和巴西蝙蝠的例子。巴西蝙蝠种类和数量都比北美的多，因为巴西蝙蝠吃的食物种类繁多。
相似TPO练习推荐：
TPO17-2: Animal Signals in The Rain Forest
TPO32-3: Distribution of Tropical Bee Colonies
相关背景学习：
Adaptations of Animals in the Tropical Rain Forest
With warm temperatures, water and an abundance of food, tropical rain forests support thousands of wildlife species. The competition means organisms must adapt or develop specialized traits to compete for environmental resources. Many rain forest animals use adaptations to carve out their own niches and protect themselves from predators.
Crafty Camouflage
Being invisible to a predator or to prey is an advantage in the tropical rain forest. One animal -- the tree sloth -- combines expert cover with slow-motion movement to dodge predators such as the jaguar. A sloth's fur is covered with green algae so it blends with the environment. It is the world's slowest moving animal and takes up to a month to digest its food, so it doesn't need many resources to survive. The boa constrictor uses its camouflaged invisibility to sneak up on prey, while tiny rain forest grasshoppers have developed near-transparent coloring to blend in with leaves.
Prime Real Estate
? The ground floor and lower canopies of the rain forest bustle with wildlife. The aptly name spider monkeys adapted to live at the top of the tree canopy where they have little competition for food, and the spider monkey's prehensile tail gives it the ability to swing gracefully from tree to tree.
Picky Eaters
? Some animals in the rain forest have adapted to a limited diet so they don't face competition for food. Toucans snag hard-to-reach fruit -- inaccessible to other feathered flyers -- with their long, narrow beaks. Parrots have incredibly sturdy bills to crack nuts and dig out hidden food. Leaf cutter ants put in a hard day's work for a meal. They carry bits of leaves 50 times their weight from high branches to the ground. They bury the leaves and eat the fungus that grows as the plant matter decomposes.
2016年10月28日托福阅读真题第二篇 Extinctions at the End of the Cretaceous(白垩纪)(生命/物质类)
【20160109&20150614】旧题
原文回顾：白垩纪的物种大灭绝。这个话题大家中文背景知道都有一定的了解。这篇文章主要关注点在于海洋生物和陆地生物，是同步减少的。首先他说，有35%的不如动物和75%的植被都在大灭绝中消失，同时在海洋中，大量的生物比如micro plankton(浮游生物)也灭绝了。这也导致了陆地上以叶子为食物链基础的食物链也断了，树木减少，恐龙赖以生存的栖息地和食物也不断下降，最终导致恐龙灭绝。但是鸟类和部分爬行动物幸存下来，因为他们是腐蚀性动物，动物尸体为他们的食物。
第二个灭绝的原因是恐龙的繁殖速度太慢，但是像鳕鱼繁殖力较大的就能存活。后面介绍了kt界层线的标志是浮游生物的数量变化。活下来的浮游生物获得一种特殊的能力。界线两边的浮游生物化石有变化。在一层沉积层中，科学家发现浮游生物化石不多，但是有一种不同的生物化石数目很多，认为两者有一定的联系。1860年间，还没有很多证据证明kt界层线的具体形成原因。同年有其他学者找到证据认为kt是因为小行星a撞击地球造成的。因为在kt中发现了很多铱元素，这种元素在a中大量存在。但是也有人认为，这种元素可能来自地球自身的火山运动产生。
相似TPO练习推荐：
TPO15-2: Mass Extinctions：跟这篇重复率很高
Online Test: Meteorite Impact and Dinosaur Extinction
TPO33-3: Extinction Episodes of the Past
TPO8-2: Extinction of The Dinosaurs
相关背景学习
The Cretaceous–Paleogene (K–Pg) extinction event, also known as the Cretaceous–Tertiary (K–T) extinction, was a mass extinction of some three-quarters of the plant and animal species on Earth that occurred over a geologically short period of time approximately 66 million years ago. With the exception of some ectothermic species like the leatherback sea turtle and crocodiles, no tetrapod weighing more than 55 pounds (25 kilos) survived. It marked the end of the Cretaceous period and with it, the entire Mesozoic Era, opening the Cenozoic Era that continues today.
In the geologic record, the K–Pg event is marked by a thin layer of sediment called the K–Pg boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust but abundant in asteroids.
As originally proposed in 1980 by a team of scientists led by Luis Alvarez, it is now generally thought that the K–Pg extinction was triggered by a massive comet or asteroid impact 66 million years ago and its catastrophic effects on the global environment, including a lingering impact winter that made it impossible for plants and plankton to carry out photosynthesis. The impact hypothesis, also known as the Alvarez hypothesis, was bolstered by the discovery of the 180-kilometre-wide (112 mi) Chicxulub crater in the Gulf of Mexico in the early 1990s, which provided conclusive evidence that the K–Pg boundary clay represented debris from an asteroid impact. The fact that the extinctions occurred at the same time as the impact provides strong situational evidence that the K–Pg extinction was caused by the asteroid. It was possibly accelerated by the creation of the Deccan Traps. However, some scientists maintain the extinction was caused or exacerbated by other factors, such as volcanic eruptions, climate change, or sea level change, separately or together.
A wide range of species perished in the K–Pg extinction. The most well-known victims are the non-avian dinosaurs. However, the extinction also destroyed a plethora of other terrestrial organisms, including certain mammals, pterosaurs, birds, lizards, insects, and plants. In the oceans, the K–Pg extinction killed off plesiosaurs and the giant marine lizards (Mosasauridae) and devastated fish, sharks, mollusks (especially ammonites, which became extinct) and many species of plankton. It is estimated that 75% or more of all species on Earth vanished. Yet the devastation caused by the extinction also provided evolutionary opportunities. In the wake of the extinction, many groups underwent remarkable adaptive radiations—a sudden and prolific divergence into new forms and species within the disrupted and emptied ecological niches resulting from the event. Mammals in particular diversified in the Paleogene, producing new forms such as horses, whales, bats, and primates. Birds, fish and perhaps lizards also radiated.
Complex Cretaceous–Paleogene clay layer (gray) in the Geulhemmergroeve tunnels near Geulhem, The Netherlands. Finger is on the actual Cretaceous-Paleogene boundary.
2016年10月28日托福阅读真题第三篇 The Origin of Earth’s Atmosphere (地球类)
旧题【20150314】 和tpo36-2一模一样!!!
相似TPO练习推荐：
TPO27-2：The Formation of Volcanic Islands
原文重现：TPO36-2 The origin of Earth’s atmosphere
In order to understand the origin of Earth's atmosphere, we must go back to the earliest days of the solar system, before the planets themselves were formed from a disk of rocky material spinning around the young Sun. This material gradually coalesced into lumps called planetesimals as gravity and chance smashed smaller pieces together, a chaotic and violent process that became more so as planetesimals grew in size and gravitational pull. Within each orbit, collisions between planetesimals generated immense heat and energy. How violent these processes were is suggested by the odd tilt and spin of many of the planets, which indicate that each of the planets was, like a billiard ball, struck at some stage by another large body of some kind. Visual evidence of these processes can be seen by looking at the Moon. Because the Moon has no atmosphere, its surface is not subject to erosion, so it retains the marks of its early history. Its face is deeply scarred by millions of meteoric impacts, as you can see on a clear night with a pair of binoculars. The early Earth did not have much of an atmosphere. Before it grew to full size, its gravitational pull was insufficient to prevent gases from drifting off into space, while the solar wind (the great stream of atomic particles emitted from the Sun) had already driven away much of the gaseous material from the inner orbits of the solar system. So we must imagine the early Earth as a mixture of rocky materials, metals, and trapped gases, subject to constant bombardment by smaller planetesimals and without much of an atmosphere.
As it began to reach full size, Earth heated up, partly because of collisions with other planetesimals and partly because of increasing internal pressures as it grew in size. In addition, the early Earth contained abundant radioactive materials, also a source of heat. As Earth heated up, its interior melted. Within the molten interior, under the influence of gravity, different elements were sorted out by density. By about 40 million years after the formation of the solar system, most of the heavier metallic elements in the early Earth, such as iron and nickel, had sunk through the hot sludge to the center giving Earth a core dominated by iron. This metallic core gives Earth its characteristic magnetic field, which has played an extremely important role in the history of our planet.
As heavy materials headed for the center of Earth, lighter silicates (such as the mineral quartz) drifted upward. The denser silicates formed Earth's mantle, a region almost 3,000 kilometers thick between the core and the crust. With the help of bombardment by comets, whose many impacts scarred and heated Earth's surface, the lightest silicates rose to Earth's surface, where they cooled more rapidly than the better- insulated materials in Earth's interior. These lighter materials, such as the rocks we call granites, formed a layer of continental crust about 35 kilometers thick. Relative to Earth as a whole, this is as thin as an eggshell. Seafloor crust is even thinner, at about 7 kilometers; thus, even continental crust reaches only about 1/200th of the way to Earth's core. Much of the early continental crust has remained on Earth's surface to the present day.
The lightest materials of all, including gases such as hydrogen and helium, bubbled through Earth's interior to the surface. So we can imagine the surface of the early Earth as a massive volcanic field. And we can judge pretty well what gases bubbled up to that surface by analyzing the mixture of gases emitted by volcanoes. These include hydrogen, helium, methane, water vapor, nitrogen, ammonia, and hydrogen sulfide. Other materials, including large amounts of water vapor, were brought in by cometary bombardments. Much of the hydrogen and helium escaped; but once Earth was fully formed, it was large enough for its gravitational field to hold most of the remaining gases, and these formed Earth's first stable atmosphere.