托福阅读TPO真题全文本 答案译文

发布时间：2016-05-30







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托福阅读TPO真题全文本+答案译文
摘要： 同学们复习托福阅读的时候是不是找不到有效的托福资料呢?今天小编告诉你个秘密，那就是所有高分考生使用的托福阅读TPO真题全文本+答案译文，小编为大家准备好了，大家一起来看看吧。
今天小编向大家推荐 托福 阅读TPO真题全文本+答案译文，此资料非常的全面，很多高分考生的成功案例都是备考此资料，赶紧一起来看看吧。
 It has long been accepted that the Americas were colonized by a migration of peoples from Asia, slowly traveling across a land bridge called Beringia (now the Bering Strait between northeastern Asia and Alaska during the last Ice Age. The first water craft theory about the migration was that around 11,000-12,000 years ago there was an ice-free corridor stretching from eastern Beringia to the areas of North America south of the great northern glaciers. It was the midcontinental corridor between two massive ice sheets-the Laurentide to the west-that enabled the southward migration. But belief in this ice-free corridor began to crumble when paleoecologist Glen MacDonald demonstrated that some of the most important radiocarbon dates used to support the existence of an ice-free corridor were incorrect. He persuasively argued that such an ice-free corridor did not exist until much later, when the continental ice began its final retreat. 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 Americans 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 Americans 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 extend 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. 1 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 from the fact that the greatest diversity in Native American languages occurs along the west coast of the Americans, suggesting that this region has been settled the longest. 以上就是小编向大家推荐的 托福阅读 TPO真题全文本+答案译文的部分精彩内容，各位考生可以点击下载按钮进行免费的资料索取，希望小编的资料能帮助到大家。
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托福阅读TPO真题全文本 答案译文

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