在日常學(xué)習(xí)、工作或生活中，大家總少不了接觸作文或者范文吧，通過文章可以把我們那些零零散散的思想，聚集在一塊。范文怎么寫才能發(fā)揮它最大的作用呢？這里我整理了一些優(yōu)秀的范文，希望對大家有所幫助，下面我們就來了解一下吧。
托福tpo閱讀文本及答案(pdf 托福閱讀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.
這種觀念被人們接受很長時間了：美洲被一群來自亞洲的移民殖民統(tǒng)治著，他們在上一個冰河時代緩慢地跨越了一個叫做白令的大陸橋(現(xiàn)在白令海峽位于東北亞和阿拉斯加之間)。關(guān)于這些遷徙的第一個水路理論表明，大概在11 000到12 000年前，有一個不凍的走廊，它從白令海峽東部延伸到北美(大北部冰河的南部)，是連在兩個巨大冰床間的半大陸性走廊，向西的laurentide使往南的遷移成為可能。但是當(dāng)古生態(tài)學(xué)者glen macdonald證明一些用來支持不凍走廊存在的重要放射性碳時間不正確時，對于不凍走廊的信念就被粉碎了。他令人信服地主張那樣的不凍走廊直到很久以后才出現(xiàn)，那時大陸冰開始最后的消退。 另外一種理論得到越來越多的人的支持，它認(rèn)為可能早在16 000年前，人們使用船只，也許是那種獸皮做的小船，從白令沿著阿拉斯加海灣，然后沿著北美的西北海岸前進(jìn)。這條路線使人類可以在大陸冰河解凍之前進(jìn)入美洲南部地區(qū)。直到20世紀(jì)70年代早期，大部分考古學(xué)家都不認(rèn)為海岸可能是進(jìn)入美洲的移民路線，因為地理學(xué)家一開始就堅信整個西北海岸在上個冰河時代是被冰川覆蓋的。人們猜測冰從阿拉斯加、加拿大山脈向西延伸到大陸架的邊界，也就是大陸延伸到海洋中而被淹沒的部分。這樣就形成了一個由冰構(gòu)成的，從阿拉斯加半島，經(jīng)過阿拉斯加海灣，向南沿著北美洲西北海岸延伸至今天的華盛頓州的冰層障礙。
海岸移民路線的最有影響力的支持者是加拿大考古學(xué)家knut fladmark。他認(rèn)為通過船只的使用，人們逐漸殖民到?jīng)]有冰凍的地方以及沿著大陸架的、由于海平面較低而裸露出來的地區(qū)。fladmark的假設(shè)從一個事實那得到了更多的支持，因為美國本土語言的最大多樣性出現(xiàn)在西海岸沿岸，這就表明這個地區(qū)是人類定居時間最早的。
更多最近的地質(zhì)研究證明了13 000年前在加拿大的不列顛可倫比亞省主要海岸地區(qū)無冰區(qū)域的存在和結(jié)冰?，F(xiàn)在研究表明，直到上個冰河時代末期，阿拉斯加?xùn)|南、沿大陸架內(nèi)的大部分地區(qū)并沒有被冰層覆蓋。一項研究表明，除了在不列顛哥倫比亞省東南部和華盛頓州之間的250英里的海岸地區(qū)以外，北美的西北海岸在大概16 000年之前都是沒有冰的。沿海的遼闊地區(qū)的冰川在大約16 000年前開始融化，這就為13 000前到14 000年前的某一段時間內(nèi)植物、動物和人類的遷移提供了一個海岸走廊。
海岸走廊假設(shè)近些年得到了越來越多的支持，因為一些大型動物(比如北美馴鹿、棕熊)的遺跡出現(xiàn)在阿拉斯加?xùn)|南部地區(qū)，其時間為10 000年到12 500年之前。之前大部分科學(xué)家認(rèn)為此時此地不適合人類生存。如果一種環(huán)境能滿足熊的繁殖，那么它就有足夠的食物來源來供應(yīng)人類的生存。fladmark和其他科學(xué)家都認(rèn)為人類第一次乘船沿著西北岸到達(dá)美洲發(fā)生在冰河時代的晚期，可能早達(dá)14 000年以前。最新的地質(zhì)資料表明：13 000年至14 000年前，人們殖民因低海平面而裸露的大陸架沿岸的無冰區(qū)域是可能的。
海岸假設(shè)提出了一個以捕食海洋哺乳動物、捕撈咸水魚類、使用船只為基礎(chǔ)的自然經(jīng)濟(jì)。由于東部是冰障，西部是太平洋，北部是移民區(qū)，所以有一股強大的力量促使人們往南方遷移。
托福tpo閱讀文本及答案(pdf 托福閱讀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.
教師被認(rèn)為受益于反思實踐——有意識地更深入思考、仔細(xì)地檢查發(fā)生在他們自己教室里的事件和相互影響。教育家t 懷爾德曼和j. 奈爾斯(1987)描述了一個在資深教師中開展反思實踐的方案。這是合理的，因為人們認(rèn)為反思的實踐可以幫助老師們更加理性地對待他們的角色和從事的事業(yè)，并可以讓他們能在教學(xué)準(zhǔn)則中處理科學(xué)事實的缺乏和知識的不確定。
懷爾德曼和奈爾斯都特別喜歡研究在哪種情況下反思可能大量出現(xiàn)——一個幾乎沒有任何文獻(xiàn)指導(dǎo)的課題。他們給弗吉利亞的一組教師設(shè)計了一個實驗策略，并在幾年內(nèi)研究了這一組的40位教師。他們擔(dān)心很多人可能認(rèn)為沉浸在這種全新的教育概念中的結(jié)果就是，發(fā)現(xiàn)教師反思的抽象概念和現(xiàn)實之間的鴻溝太大而無法逾越。要反思像教學(xué)這樣復(fù)雜的事件不是容易的。老師們都參加了關(guān)于教學(xué)事件計劃的討論，緊接著在工作人員的協(xié)助下去反思具體問題，然后是獨立反思。
懷爾德曼和奈爾斯觀察到系統(tǒng)教學(xué)反思需要一種以客觀的方式來理解教室里發(fā)生事件的能力。他們起初認(rèn)為參與研究的教師們太功利，并不是足夠豐富和詳細(xì)以促使系統(tǒng)反思的產(chǎn)生。教師們很少有機會和時間去客觀地觀察他們自己和其他老師的教學(xué)。更深的研究發(fā)現(xiàn)教師們更愿意評價事件而不是站在事件之外洞察一個事件的促進(jìn)因素。
幫助這組教師修訂他們關(guān)于課堂事件的認(rèn)識變成了關(guān)鍵問題。這個過程需要時間和耐心以及有效的受訓(xùn)者。研究者認(rèn)為訓(xùn)練同一個教師使他客觀地看待事情需要大約20到30小時，而反思技巧的練習(xí)同樣需要這么多時間。
懷爾德曼和奈爾斯確定了促進(jìn)在教學(xué)環(huán)境中實現(xiàn)反思行為的3個原則。第一就是來自教學(xué)系統(tǒng)管理層的支持，這使得教師們明白反思實踐的必要條件，并知道它與教學(xué)之間的聯(lián)系。第二就是需要足夠的時間和空間。項目中的教師們抱怨說讓他們放棄別人當(dāng)時的要求而為自己騰出時間去提升自己的反思能力是很困難的。第三就是以其他教師的支持為基礎(chǔ)的親密無間的環(huán)境。項目中的教師同樣需要支持和鼓勵以幫助他們?nèi)?yīng)付他們職業(yè)生活中的不如意的方面。懷爾德曼和奈爾斯作出了一個總結(jié)性的評論：―或許我們學(xué)到的最重要的觀點就是教師不會因為這是好的，或者甚至是不可或缺的觀念而自發(fā)地開展教學(xué)反思?！?/p>
懷爾德曼和奈爾斯的工作表明認(rèn)識進(jìn)行反思的某些困難的重要性。也有其他人知道這個，并指出相似的關(guān)于反思行為的教學(xué)職業(yè)文化阻礙。zeichner 和liston(1987)指出作為一個決策者的教師和作為一個將其他人觀念付諸實施的教師之間，存在著角色上的不一致。比文化問題更基本的是動機問題。成為一個反
思教學(xué)的執(zhí)行者需要額外的付出(jaworski,1993)而且只有一個模糊的目標(biāo)，甚至不僅沒有顯而易見的回報，反而有易受責(zé)難的威脅。很少人直接質(zhì)疑什么可能讓一個教師想變成反思型教師。顯然，使教師朝著反思行為奮斗的最直接的原因是師資培訓(xùn)者認(rèn)為這是一件很好的事情。關(guān)于反思的動力存在許多未知的問題，例如外部驅(qū)動的反思的價值與通過習(xí)慣進(jìn)行反思的價值是不同的。
托福tpo閱讀文本及答案(pdf 托福閱讀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.
大約500萬年以前，當(dāng)夏威夷群島作為火山從海洋中出現(xiàn)的時候，它們與其他大陸相距甚遠(yuǎn)。然后，經(jīng)過了炙熱陽光和濕潤雨水的交替作用之后，那荒蕪的黑色的巖石表面開始漸漸地變軟。最后，大風(fēng)就攜帶來了各種各樣的生命。 孢子很輕，可以被微風(fēng)攜帶著從更古老的陸地飄過幾千英里并隨機地降落在荒蕪的山腰上。一些孢子在漆黑堅硬的巖石中找到了立足點，并生長起來，開始改造土地。地衣可能就是第一批成功安家的植物，它們不是單一的一種植物，每一個都是海藻和真菌的共生體。海藻通過光合作用獲取太陽的能量，并將它儲存在有機的分子中。真菌從巖石中吸收水分和礦物鹽，并將這些作為代謝廢物為海藻施肥。島嶼上的最早的生物群落以共生的方式存在是非常重要的。共生是一種依靠兩種或兩種以上的生物緊密合作而生存的現(xiàn)象，也是島嶼上生物群落非常重要的一項原則。
地衣有利于加速堅硬的巖石表面的分解，并產(chǎn)生了一層柔軟的土壤，這些土壤可以提供熔融巖石含有的來自地球內(nèi)部的豐富的礦物質(zhì)?，F(xiàn)在其他形式的生命就可以安家了：蕨類植物和苔蘚(兩種最古老的陸地植物品種)甚至可以在巖石縫隙里繁衍。這些植物通過產(chǎn)生孢子來繁殖，孢子是一些微小的有營養(yǎng)的細(xì)胞，它們攜帶了所有的用于生長一株新的植物的遺傳物質(zhì)，但是它沒有任何外部表皮的保護(hù)，也沒攜帶供應(yīng)營養(yǎng)的組織。大量的包子降落在母體植物下面的土地上，有時候它們被流水和風(fēng)帶到了更遠(yuǎn)的地方。但是只有很少的停駐在絕好的地方的孢子可以開始新的生命，絕大部分的孢子會落在不含礦物的巖層上。占著絕對數(shù)量
上的優(yōu)勢，蕨類植物和地衣到達(dá)了夏威夷群島存活下來，并繁衍開去。其中一些物種體型巨大，成為橛子樹，它們甚至現(xiàn)在還生長在夏威夷的森林中。
在蕨類植物進(jìn)化了好幾百萬年之后(不過，還是遠(yuǎn)在夏威夷群島出現(xiàn)之前)另一種植物開始在地球上進(jìn)化：種子植物。這是一次驚人的生物進(jìn)化，種子有一層裹在遺傳物質(zhì)外面的'表皮，在表皮里面是一種濃縮了的營養(yǎng)物質(zhì)。因此，種子物種的成活率相對于那些裸露的孢子大大地提高了。其中一種種子植物——被子植物，包含了所有的開花植物。在被子植物中，種子被另外的一層外皮包裹著。其中的一些表皮很堅硬—就像堅果的外殼—可以提供額外的保護(hù)。有一些則很軟、誘人，比如桃子或櫻桃。還有一些被子植物的種子攜帶有薄紗一樣的翅膀，比如說蒲公英和馬利筋的種子。這種特征為種子轉(zhuǎn)移到新的棲息地提供了更好的途徑，它們可以通過空氣、流水傳播并可以保存好幾個月。
一些擁有碩大的、可以浮于水面的種子的植物，像椰子，隨洋流飄蕩，被沖上海岸。對洋流變動抵抗的耐久性使得他們可以在海水的長期浸泡中生存下來。當(dāng)他們停歇在溫暖的海灘上，一旦條件合適，種子的外皮就開始變軟。由于受到內(nèi)部攜帶的營養(yǎng)物質(zhì)的滋養(yǎng)，幼小的植物伸長出他們的根部，并開始在陽光下成長。
借助這些種子，植物傳播到更遠(yuǎn)的新地方，甚至是像夏威夷群島這樣的孤立的群島上。夏威夷群島位于加利福利亞以西2 000英里和日本以東3 500英里。草、花和開花植物的種子經(jīng)過長途跋涉到達(dá)這些島嶼上(草類是一類將其種子孕育在長長的秸稈中的簡單被子植物)。在短得驚人的時間內(nèi)，被子植物覆蓋了大面積的夏威夷群島上曾經(jīng)荒蕪的地面。
