【托福阅读】2012年12月22日托福阅读真题（附讲解视频 ）

兔斯基

2012年12月22日托福考试真题分享——阅读部分



　　TOPIC：鸟类叫声
　　讲鸟怎么学唱歌，三种方式：遗传；听自己唱然后不断纠正；听别个成年鸟唱然后学。证明遗传是说有些鸟把蛋下在别个窝里，然后幼鸟由别个养大但是一样能唱歌；证明学习时说聋鸟虽然也能唱但是不完整。最后说鸟的唱歌很精确到有很多dialect，然后鸟夫妻们利用这种dialect的区别来找到对方。最后一段是说他们之间相互模仿能够达到唱到一样的程度。
　　幼鸟学声
　　The songs of different species of birds vary and are generally typical of the species. In modern-day biology, bird song is typically analyzed using a sound spectrograph. Species vary greatly in the complexity of their songs and in the number of distinct kinds of song they sing (up to 3000 in the Brown Thrasher); individuals within some species vary in the same way. In a few species, such as lyrebirds and mockingbirds, songs imbed arbitrary elements learned in the individual's lifetime, a form of mimicry (though maybe better called "appropriation" [Ehrlich et al.], as the bird does not pass for another species). As early as 1773, it was established that birds learned calls, and cross-fostering experiments succeeded in making linnet Acanthis cannabina learn the song of a skylark, Alauda arvensis.⑴In many species, it appears that although the basic song is the same for all members of the species, young birds learn some details of their songs from their fathers, and these variations build up over generations to form dialects.⑵
　　Song learning in juvenile birds occurs in two stages: sensory learning, which involves the juvenile listening to the father or other conspecific bird and memorizing the spectral and temporal qualities of the song (song template), and sensorimotor learning, which involves the juvenile bird producing its own vocalizations and practicing its song until it accurately matches the memorized song template.⑶During the sensorimotor learning phase, song production begins with highly variable sub-vocalizations called "sub-song", which is akin to babbling in human infants. Soon after, the juvenile song shows certain recognizable characteristics of the imitated adult song, but still lacks the stereotypy of the crystallized song – this is called "plastic song".⑷Finally, after two or three months of song learning and rehearsal (depending on species), the juvenile produces a crystallized song, characterized by spectral and temporal stereotypy (very low variability in syllable production and syllable order).⑸Some birds, such as Zebra Finches, which are the most popular species for birdsong research, have overlapping sensory and sensorimotor learning stages.⑹
　　Research has indicated that birds' acquisition of song is a form of motor learning that involves regions of the basal ganglia. Further, the PDP has been considered homologous to a mammalian motor pathway originating in the cerebral cortex and descending through the brain stem, while the AFP has been considered homologous to the mammalian cortical pathway through the basal ganglia and thalamus.⑺Models of bird-song motor learning can be useful in developing models for how humans learn speech.⑻In some species such as Zebra Finches, learning of song is limited to the first year; they are termed "age-limited" or "close-ended" learners. Other species such as the canaries can develop new songs even as sexually mature adults; these are termed "open-ended" learners.⑼⑽
　　Researchers have hypothesized that learned songs allow the development of more complex songs through cultural interaction, thus allowing intraspecies dialects that help birds to identify kin and to adapt their songs to different acoustic environments.⑾
　　鸟类方言
　　The Dialects of Birds⑿
　　BIRDS sing in dialects as distinct to the avian ear as the difference between a Boston and Mississippi accent is to humans. But there has been a long debate over the significance, if any, of local differences in the songs of a particular species.
　　According to one major theory, birds are inclined to choose a mate with the same dialect because that helps keep the local group together, thus selectively preserving inborn behavior patterns and capabilities that are most succesful in coping with the local environment.
　　Scientists studying brown-headed cowbirds have developed a new theory. They believe the female bird cocks an educated ear to the accent of the male in choosing her mate, not so much from chauvinism as from the assurance that the right song means that the male is biologically fit.
　　The new idea is proposed in the ornithological journal Condor by Stephen I. Rothstein of the University of California at Santa Barbara and Robert C. Fleischer of the University of Hawaii. Their theory is based on observations of the brown-headed cowbird in the eastern Sierra Nevadas. Cowbirds are notorious among bird fanciers because they lay their eggs in the nests of other species, thus shirking the duties of parenthood.
　　The birds also have a considerable repertoire of sounds, including whistles in flight and elaborate songs used when they perch together. The female cowbirds respond respond more frequently to the local dialect than to males with a ''foreign'' accent.
　　The scientists said it seemed to be difficult for a cowbird to learn a new dialect. If that is the case, they argue, the female is assured by the local accent that the male is mature and has been around long enough to demonstrate an ability to defend its local territory - in short, a biologically fit mate.
　　Does this have any relevance to human accents? The researchers leave that conjecture to others.

兔斯基

　　TOPIC：海龟导航
　　科学家们研究海龟迁徙靠什么指引方向。开始一种结论是靠星星，可是海龟视力不好，很难看到，而且在乌云密布的晚上还是可以继续迁徙（乌云密布这里有道词汇题）；然后还有一种是靠气味，可是气味不能维持很久，所以不适用于长途迁徙，而且在过程中有气味干扰，但是海龟依然能找对方向；第三种是磁场，可是如果绑个磁铁在领头的海龟上，它还是可以辨别方向，所以也不是磁场。
　　但是有一个结论是海龟可能是用combine几种方法，在靠近目的地时味道是有用的（有题）。最后一种解释，是海龟体内的一种DNA，它能记录海龟被孵化出的地点（也就是他们去的地方），并且由母海龟遗传给小海龟。最后说有一个例子可以证明：从前在加勒比海的一个地方有很多绿海龟，但是后来捕杀很严重海龟们就不去了；近几年虽然又保护起来了但是海龟们来得仍然很少。
　　Orientation and Navigation of Sea Turtles⒀
　　Long-distance migrations of animals represent one of the great wonders of the natural world.  In the marine environment, migratory movements sometimes reach astonishing extremes: for example, some sea turtles, salmon, sharks, and elephant seals travel distances that exceed the width of oceans before returning to their home areas to reproduce.  How animals find their way during such migrations has remained a central mystery of sensory and behavioral biology.
　　Sea turtles are among the most impressive navigators in the animal kingdom. As hatchlings, turtles that have never before been in the ocean are able to establish unerring courses towards the open sea and then maintain their headings after swimming beyond sight of land.  Young turtles follow complex migratory pathways that often lead across enormous expanses of seemingly featureless ocean. After completing their years in the open sea, juvenile turtles take up residence in coastal feeding grounds and show great fidelity to their feeding sites, homing back to specific locations after long migrations and experimental displacements.  Similar navigational abilities exist in adult turtles, which migrate considerable distances between specific feeding areas and nesting beaches.
　　The longest and most spectacular migrations are made by young loggerhead turtles. The journey begins when the hatchlings, each no bigger than a child's hand, dig their way out of their underground nests on the beach and enter the sea. During the vast migration that follows, turtles travel for a period of years along migratory routes that span entire oceans. Young loggerheads in the North Atlantic cover more than 9,000 miles (15,000 kilometers) before returning to the North American coast. Those in the Pacific travel even farther.
　　How can young sea turtles with no prior migratory experience guide themselves across an entire ocean and back? Considerable progress has been made toward understanding how young loggerheads in the Atlantic Ocean navigate.  To learn about how baby loggerheads guide themselves during their first migration, follow the hatchling links.
　　Hatchlings embark on an impressive transoceanic migration, but they do not navigate to targets more specific than broad oceanic regions.  In contrast, older turtles acquire an ability to pinpoint specific geographic locations such as feeding areas and nesting beaches.  Recent experiments have demonstrated that sea turtles possess a remarkable ability to exploit positional information in the Earth's magnetic field as a kind of navigational map that can be used to guide movements toward specific goals.

兔斯基

　　TOPIC 地方性风的形成
　　第一是sea wind和 land wind，由于海边和陆地的温度差异产生风，夏天比较频繁，冬天少，赤道比较频繁，高纬度地区少。第二是mountain wind和 valley wind。开头先解释什么是 local wind，并说其实并不local而是一个大系统的一部分（有题）。后面主要讲了两种风： sea-land wind 和valley-mountain wind。白天陆地升温快形成低气压，于是风从海往陆地吹，能够降低陆地温度；晚上陆地降温快形成高气压于是风从陆地往海吹。这一现象跟纬度有关系，热带最明显，中纬度就不那么强烈，高纬度就几乎注意不到。第二种风，白天山面的空气受热快向上爬升形成 valley wind，这个风会产生雷阵雨；晚上反之形成mountain wind （有题，问 mountain wind的原理是什么），这个风很冷会冻伤农作物（有题）。
　　Sea and Land Breezes
　　A: Sea breeze (occurs at daytime), B: Land breeze (occurs at night)
　　In coastal regions, sea breezes and land breezes can be important factors in a location's prevailing winds. The sea is warmed by the sun more slowly because of water's greater specific heat compared to land.[43] As the temperature of the surface of the land rises, the land heats the air above it by conduction. The warm air is less dense than the surrounding environment and so it rises. This causes a pressure gradient of about 2 millibars from the ocean to the land. The cooler air above the sea, now with higher sea level pressure, flows inland into the lower pressure, creating a cooler breeze near the coast. When large-scale winds are calm, the strength of the sea breeze is directly proportional to the temperature difference between the land mass and the sea. If an offshore wind of 8 knots (15 km/h) exists, the sea breeze is not likely to develop.
　　At night, the land cools off more quickly than the ocean because of differences in their specific heat values. This temperature change causes the daytime sea breeze to dissipate. When the temperature onshore cools below the temperature offshore, the pressure over the water will be lower than that of the land, establishing a land breeze, as long as an onshore wind is not strong enough to oppose it.⒁
　　Near mountains
　　Mountain wave schematic. The wind flows towards a mountain and produces a first oscillation (A). A second wave occurs further away and higher. The lenticular clouds form at the peak of the waves (B).
　　Over elevated surfaces, heating of the ground exceeds the heating of the surrounding air at the same altitude above sea level, creating an associated thermal low over the terrain and enhancing any thermal lows that would have otherwise existed,⒂and changing the wind circulation of the region. In areas where there is rugged topography that significantly interrupts the environmental wind flow, the wind circulation between mountains and valleys is the most important contributor to the prevailing winds. Hills and valleys substantially distort the airflow by increasing friction between the atmosphere and landmass by acting as a physical block to the flow, deflecting the wind parallel to the range just upstream of the topography, which is known as a barrier jet. This barrier jet can increase the low level wind by 45%.⒃Wind direction also changes because of the contour of the land.