最新托福tpo阅读文本及答案(pdf 托福阅读tpo20(实用3篇)

托福tpo阅读文本及答案(pdf 托福阅读tpo20篇一

support is growing for the alternative theory that people using watercraft, possibly skin boats, moved southward from beringia along the gulf of alaska and then southward along the northwest coast of north america possibly as early as 16,000 years ago. this route would have enabled humans to enter southern areas of the americas prior to the melting of the continental glaciers. until the early 1970s,most archaeologists did not consider the coast a possible migration route into the americas because geologists originally believed that during the last ice age the entire northwest coast was covered by glacial ice. it had been assumed that the ice extended westward from the alaskan/canadian mountains to the very edge of the continental shelf, the flat, submerged part of the continent that extends into the ocean. this would have created a barrier of ice extending from the alaska peninsula, through the gulf of alaska and southward along the northwest coast of north america to what is today the state of washington.

the most influential proponent of the coastal migration route has been canadian archaeologist knut fladmark. he theorized that with the use of watercraft, people gradually colonized unglaciated refuges and areas along the continental shelf exposed by the lower sea level. fladmark’s hypothesis received additional support form from the fact that the greatest spanersity in native american languages occurs along the west coast of the americas, suggesting that this region has been settled the longest.

more recent geologic studies documented deglaciation and the existence of ice-free areas throughout major coastal areas of british columbia, canada, by 13,000 years ago. research now indicates that sizable areas of southeastern alaska along the inner continental shelf were not covered by ice toward the end of the last ice age. one study suggests that except for a 250-mile coastal area between southwestern british columbia and washington state, the northwest coast of north america was largely free of ice by approximately 16,000 years ago. vast areas along the coast may have been deglaciated beginning around 16,000 years ago, possibly providing a coastal corridor for the movement of plants, animals, and humans sometime between 13,000 and 14,000 years ago.

the coastal hypothesis has gained increasing support in recent years because the remains of large land animals, such as caribou and brown bears, have been found in southeastern alaska dating between 10,000 and 12,500 years ago. this is the time period in which most scientists formerly believed the area to be inhospitable for humans. it has been suggested that if the environment were capable of supporting breeding populations of bears, there would have been enough food resources to support humans. fladmark and other believe that the first human colonization of america occurred by boat along the northwest coast during the very late ice age, possibly as early as 14,000 years ago. the most recent geologic evidence indicates that it may have been possible for people to colonize ice-free regions along the continental shelf that were still exposed by the lower sea level between13,000 and 14,000 years ago.

the coastal hypothesis suggests an economy based on marine mammal hunting, saltwater fishing, shellfish gathering, and the use of watercraft. because of the barrier of ice to the east, the pacific ocean to the west, and populated areas to the north, there may have been a greater impetus for people to move in a southerly direction.

这种观念被人们接受很长时间了：美洲被一群来自亚洲的移民殖民统治着，他们在上一个冰河时代缓慢地跨越了一个叫做白令的大陆桥(现在白令海峡位于东北亚和阿拉斯加之间)。关于这些迁徙的第一个水路理论表明，大概在11 000到12 000年前，有一个不冻的走廊，它从白令海峡东部延伸到北美(大北部冰河的南部)，是连在两个巨大冰床间的半大陆性走廊，向西的laurentide使往南的迁移成为可能。但是当古生态学者glen macdonald证明一些用来支持不冻走廊存在的重要放射性碳时间不正确时，对于不冻走廊的信念就被粉碎了。他令人信服地主张那样的不冻走廊直到很久以后才出现，那时大陆冰开始最后的消退。另外一种理论得到越来越多的人的支持，它认为可能早在16 000年前，人们使用船只，也许是那种兽皮做的小船，从白令沿着阿拉斯加海湾，然后沿着北美的西北海岸前进。这条路线使人类可以在大陆冰河解冻之前进入美洲南部地区。直到20世纪70年代早期，大部分考古学家都不认为海岸可能是进入美洲的移民路线，因为地理学家一开始就坚信整个西北海岸在上个冰河时代是被冰川覆盖的。人们猜测冰从阿拉斯加、加拿大山脉向西延伸到大陆架的边界，也就是大陆延伸到海洋中而被淹没的部分。这样就形成了一个由冰构成的，从阿拉斯加半岛，经过阿拉斯加海湾，向南沿着北美洲西北海岸延伸至今天的华盛顿州的冰层障碍。

海岸移民路线的最有影响力的支持者是加拿大考古学家knut fladmark。他认为通过船只的使用，人们逐渐殖民到没有冰冻的地方以及沿着大陆架的、由于海平面较低而裸露出来的地区。fladmark的假设从一个事实那得到了更多的支持，因为美国本土语言的最大多样性出现在西海岸沿岸，这就表明这个地区是人类定居时间最早的。

更多最近的地质研究证明了13 000年前在加拿大的不列颠可伦比亚省主要海岸地区无冰区域的存在和结冰。现在研究表明，直到上个冰河时代末期，阿拉斯加东南、沿大陆架内的大部分地区并没有被冰层覆盖。一项研究表明，除了在不列颠哥伦比亚省东南部和华盛顿州之间的250英里的海岸地区以外，北美的西北海岸在大概16 000年之前都是没有冰的。沿海的辽阔地区的冰川在大约16 000年前开始融化，这就为13 000前到14 000年前的某一段时间内植物、动物和人类的迁移提供了一个海岸走廊。

海岸走廊假设近些年得到了越来越多的支持，因为一些大型动物(比如北美驯鹿、棕熊)的遗迹出现在阿拉斯加东南部地区，其时间为10 000年到12 500年之前。之前大部分科学家认为此时此地不适合人类生存。如果一种环境能满足熊的繁殖，那么它就有足够的食物来源来供应人类的生存。fladmark和其他科学家都认为人类第一次乘船沿着西北岸到达美洲发生在冰河时代的晚期，可能早达14 000年以前。最新的地质资料表明：13 000年至14 000年前，人们殖民因低海平面而裸露的大陆架沿岸的无冰区域是可能的。

海岸假设提出了一个以捕食海洋哺乳动物、捕捞咸水鱼类、使用船只为基础的自然经济。由于东部是冰障，西部是太平洋，北部是移民区，所以有一股强大的力量促使人们往南方迁移。

托福tpo阅读文本及答案(pdf 托福阅读tpo20篇二

teachers, it is thought, benefit from the practice of reflection, the conscious act of thinking deeply about and carefully examining the interactions and events within their own classrooms. educators t. wildman and j. niles (1987) describe a scheme for developing reflective practice in experienced teachers. this was justified by the view that reflective practice could help teachers to feel more intellectually involved in their role and work in teaching and enable them to cope with the paucity of scientific fact and the uncertainty of knowledge in the discipline of teaching.

wildman and niles were particularly interested in investigating the conditions under which reflection might flourish–a subject on which there is little guidance in the literature. they designed an experimental strategy for a group of teachers in virginia and worked with 40 practicing teachers over several years. they were concerned that many would be ―drawn to these new, refreshing‖conceptions of teaching only to find that the void between the abstractions and the realities of teacher reflection is too great to bridge. reflection on a complex task such as teaching is not easy.‖the teachers were taken through a program of talking about teaching events, moving on to reflecting about specific issues in a supported, and later an independent, manner. wildman and niles observed that systematic reflection on teaching required a sound ability to understand classroom events in an objective manner. they describe the initial understanding in the teachers with whom they were working as being ―utilitarian …and not rich or detailed enough to drive systematic reflection.‖teachers rarely have the time or opportunities to view their own or the teaching of others in an objective manner. further observation revealed the tendency of teachers to evaluate events rather than review the contributory factors in a considered manner by, in effect, standing outside the situation.

helping this group of teachers to revise their thinking about classroom events became central. this process took time and patience and effective trainers. the researchers estimate that the initial training of the teachers to view events objectively took between 20 and 30 hours, with the same number of hours again being required to practice the skills of reflection.

wildman and niles identify three principles that facilitate reflective practice in a teaching situation. the first is support from administrators in an education system, enabling teachers to understand the requirements of reflective practice and how it relates to teaching students. the second is the availability of sufficient time and space. the teachers in the program described how they found it difficult to put aside the immediate demands of others in order to give themselves the time they needed to

develop their reflective skills. the third is the development of a collaborative environment with support from other teachers. support and encouragement were also required to help teachers in the program cope with aspects of their professional life with which they were not comfortable. wildman and niles make a summary comment: ―perhaps the most important thing we learned is the idea of the teacher-as-reflective-practitioner will not happen simply because it is a good or even compelling idea.‖

the work of wildman and niles suggests the importance of recognizing some of the difficulties of instituting reflective practice. others have noted this, making a similar point about the teaching profession’s cultural inhibitions about reflective practice. zeichner and liston (1987) point out the inconsistency between the role of the teacher as a (reflective) professional decision maker and the more usual role of the teacher as a technician, putting into practice the ideas of theirs. more basic than the cultural issues is the matter of motivation. becoming a reflective practitioner requires extra work (jaworski, 1993) and has only vaguely defined goals with, perhaps, little initially perceivable reward and the threat of vulnerability. few have directly questioned what might lead a teacher to want to become reflective. apparently, the most obvious reason for teachers to work toward reflective practice is that teacher educators think it is a good thing. there appear to be many unexplored matters about the motivation to reflect –for example, the value of externally motivated reflection as opposed to that of teachers who might reflect by habit.

教师被认为受益于反思实践——有意识地更深入思考、仔细地检查发生在他们自己教室里的事件和相互影响。教育家t 怀尔德曼和j. 奈尔斯(1987)描述了一个在资深教师中开展反思实践的方案。这是合理的，因为人们认为反思的实践可以帮助老师们更加理性地对待他们的角色和从事的事业，并可以让他们能在教学准则中处理科学事实的缺乏和知识的不确定。

怀尔德曼和奈尔斯都特别喜欢研究在哪种情况下反思可能大量出现——一个几乎没有任何文献指导的课题。他们给弗吉利亚的一组教师设计了一个实验策略，并在几年内研究了这一组的40位教师。他们担心很多人可能认为沉浸在这种全新的教育概念中的结果就是，发现教师反思的抽象概念和现实之间的鸿沟太大而无法逾越。要反思像教学这样复杂的事件不是容易的。老师们都参加了关于教学事件计划的讨论，紧接着在工作人员的协助下去反思具体问题，然后是独立反思。

怀尔德曼和奈尔斯观察到系统教学反思需要一种以客观的方式来理解教室里发生事件的能力。他们起初认为参与研究的教师们太功利，并不是足够丰富和详细以促使系统反思的产生。教师们很少有机会和时间去客观地观察他们自己和其他老师的教学。更深的研究发现教师们更愿意评价事件而不是站在事件之外洞察一个事件的促进因素。

帮助这组教师修订他们关于课堂事件的认识变成了关键问题。这个过程需要时间和耐心以及有效的受训者。研究者认为训练同一个教师使他客观地看待事情需要大约20到30小时，而反思技巧的练习同样需要这么多时间。

怀尔德曼和奈尔斯确定了促进在教学环境中实现反思行为的3个原则。第一就是来自教学系统管理层的支持，这使得教师们明白反思实践的必要条件，并知道它与教学之间的联系。第二就是需要足够的时间和空间。项目中的教师们抱怨说让他们放弃别人当时的要求而为自己腾出时间去提升自己的反思能力是很困难的。第三就是以其他教师的支持为基础的亲密无间的环境。项目中的教师同样需要支持和鼓励以帮助他们去应付他们职业生活中的不如意的方面。怀尔德曼和奈尔斯作出了一个总结性的评论：―或许我们学到的最重要的观点就是教师不会因为这是好的，或者甚至是不可或缺的观念而自发地开展教学反思。‖

怀尔德曼和奈尔斯的工作表明认识进行反思的某些困难的重要性。也有其他人知道这个，并指出相似的关于反思行为的教学职业文化阻碍。zeichner 和liston(1987)指出作为一个决策者的教师和作为一个将其他人观念付诸实施的教师之间，存在着角色上的不一致。比文化问题更基本的是动机问题。成为一个反

思教学的执行者需要额外的付出(jaworski,1993)而且只有一个模糊的目标，甚至不仅没有显而易见的回报，反而有易受责难的威胁。很少人直接质疑什么可能让一个教师想变成反思型教师。显然，使教师朝着反思行为奋斗的最直接的原因是师资培训者认为这是一件很好的事情。关于反思的动力存在许多未知的问题，例如外部驱动的反思的价值与通过习惯进行反思的价值是不同的。

托福tpo阅读文本及答案(pdf 托福阅读tpo20篇三

when the hawaiian islands emerged from the sea as volcanoes, starting about five million years ago, they were far removed from other landmasses. then, as blazing sunshine alternated with drenching rains, the harsh, barren surfaces of the black rocks slowly began to soften. winds brought a variety of life-forms.

spores light enough to float on the breezes were carried thousands of miles from more ancient lands and deposited at random across the bare mountain flanks. a few of these spores found a toehold on the dark, forbidding rocks and grew and began to work their transformation upon the land. lichens were probably the first successful flora. these are not single inspanidual plants; each one is a symbiotic combination of an alga and a fungus. the algae capture the sun's energy by photosynthesis and store it in organic molecules. the fungi absorb moisture and mineral salts from the rocks, passing these on in waste products that nourish algae. it is significant that the earliest living things that built communities on these islands are examples of symbiosis, a phenomenon that depends upon the close cooperation of two or more forms of life and a principle that is very important in island communities.

lichens helped to speed the decomposition of the hard rock surfaces, preparing a soft bed of soil that was abundantly supplied with minerals that had been carried in the molten rock from the bowels of earth. now, other forms of life could take hold: ferns and mosses (two of the most ancient types of land plants) that flourish even in rock crevices. these plants propagate by producing spores–tiny fertilized cells that

contain all the instructions for making a new plant–but the spore are unprotected by any outer coating and carry no supply of nutrient. vast numbers of them fall on the ground beneath the mother plants. sometimes they are carried farther afield by water or by wind. but only those few spores that settle down in very favorable locations can start new life; the vast majority fall on barren ground. by force of sheer numbers, however, the mosses and ferns reached hawaii, survived, and multiplied. some species developed great size, becoming tree ferns that even now grow in the hawaiian forests.

many millions of years after ferns evolved (but long before the hawaiian islands were born from the sea), another kind of flora evolved on earth: the seed-bearing plants. this was a wonderful biological invention. the seed has an outer coating that surrounds the genetic material of the new plant, and inside this covering is a concentrated supply of nutrients. thus the seed’s chances of survival are greatly enhanced over those of the naked spore. one type of seed-bearing plant, the angiosperm, includes all forms of blooming vegetation. in the angiosperm the seeds are wrapped in an additional layer of covering. some of these coats are hard–like the shell of a nut–for extra protection. some are soft and tempting, like a peach or a cherry. in some angiosperms the seeds are equipped with gossamer wings, like the dandelion and milkweed seeds. these new characteristics offered better ways for the seed to move to new habitats. they could travel through the air, float in water, and lie dormant for many months.

plants with large, buoyant seeds—like coconuts—drift on ocean currents and are washed up on the shores. remarkably resistant to the vicissitudes of ocean travel, they can survive prolonged immersion in saltwater when they come to rest on warm beaches and the conditions are favorable, the seed coats soften. nourished by their imported supply of nutrients, the young plants push out their roots and establish their place in the sun.

by means of these seeds, plants spread more widely to new locations, even to isolated islands like the hawaiian archipelago, which lies more than 2,000 miles west of california and 3,500 miles east of japan. the seeds of grasses, flowers, and blooming trees made the long trips to these islands. (grasses are simple forms of angiosperms that bear their encapsulated seeds on long stalks.) in a surprisingly short time, angiosperms filled many of the land areas on hawaii that had been bare.

大约500万年以前，当夏威夷群岛作为火山从海洋中出现的时候，它们与其他大陆相距甚远。然后，经过了炙热阳光和湿润雨水的交替作用之后，那荒芜的黑色的岩石表面开始渐渐地变软。最后，大风就携带来了各种各样的生命。孢子很轻，可以被微风携带着从更古老的陆地飘过几千英里并随机地降落在荒芜的山腰上。一些孢子在漆黑坚硬的岩石中找到了立足点，并生长起来，开始改造土地。地衣可能就是第一批成功安家的植物，它们不是单一的一种植物，每一个都是海藻和真菌的共生体。海藻通过光合作用获取太阳的能量，并将它储存在有机的分子中。真菌从岩石中吸收水分和矿物盐，并将这些作为代谢废物为海藻施肥。岛屿上的最早的生物群落以共生的方式存在是非常重要的。共生是一种依靠两种或两种以上的生物紧密合作而生存的现象，也是岛屿上生物群落非常重要的一项原则。

地衣有利于加速坚硬的岩石表面的分解，并产生了一层柔软的土壤，这些土壤可以提供熔融岩石含有的来自地球内部的丰富的矿物质。现在其他形式的生命就可以安家了：蕨类植物和苔藓(两种最古老的陆地植物品种)甚至可以在岩石缝隙里繁衍。这些植物通过产生孢子来繁殖，孢子是一些微小的有营养的细胞，它们携带了所有的用于生长一株新的植物的遗传物质，但是它没有任何外部表皮的保护，也没携带供应营养的组织。大量的包子降落在母体植物下面的土地上，有时候它们被流水和风带到了更远的地方。但是只有很少的停驻在绝好的地方的孢子可以开始新的生命，绝大部分的孢子会落在不含矿物的岩层上。占着绝对数量

上的优势，蕨类植物和地衣到达了夏威夷群岛存活下来，并繁衍开去。其中一些物种体型巨大，成为橛子树，它们甚至现在还生长在夏威夷的森林中。

在蕨类植物进化了好几百万年之后(不过，还是远在夏威夷群岛出现之前)另一种植物开始在地球上进化：种子植物。这是一次惊人的生物进化，种子有一层裹在遗传物质外面的'表皮，在表皮里面是一种浓缩了的营养物质。因此，种子物种的成活率相对于那些裸露的孢子大大地提高了。其中一种种子植物——被子植物，包含了所有的开花植物。在被子植物中，种子被另外的一层外皮包裹着。其中的一些表皮很坚硬—就像坚果的外壳—可以提供额外的保护。有一些则很软、诱人，比如桃子或樱桃。还有一些被子植物的种子携带有薄纱一样的翅膀，比如说蒲公英和马利筋的种子。这种特征为种子转移到新的栖息地提供了更好的途径，它们可以通过空气、流水传播并可以保存好几个月。

一些拥有硕大的、可以浮于水面的种子的植物，像椰子，随洋流飘荡，被冲上海岸。对洋流变动抵抗的耐久性使得他们可以在海水的长期浸泡中生存下来。当他们停歇在温暖的海滩上，一旦条件合适，种子的外皮就开始变软。由于受到内部携带的营养物质的滋养，幼小的植物伸长出他们的根部，并开始在阳光下成长。

借助这些种子，植物传播到更远的新地方，甚至是像夏威夷群岛这样的孤立的群岛上。夏威夷群岛位于加利福利亚以西2 000英里和日本以东3 500英里。草、花和开花植物的种子经过长途跋涉到达这些岛屿上(草类是一类将其种子孕育在长长的秸秆中的简单被子植物)。在短得惊人的时间内，被子植物覆盖了大面积的夏威夷群岛上曾经荒芜的地面。