『新东方在线托福阅读』为托福考生准备了ETS托福TPO/Official 9 Passage 1阅读练习：Paragraph 2 begins by presenting a theory and then goes on to真题题目及答案解析，TPO/Official 9 Passage 1阅读原文范文音频翻译

托福TPO/Official 9 Passage 1阅读原文Paragraph 2 begins by presenting a theory and then goes on to题目答案及解析-新东方托福官方网校手机版

Colonizing the Americas via the Northwest Coast

人们一直以来认为上一个冰河世纪时期，来自亚洲的移民通过缓慢跨越白令陆桥殖民了美洲（当今连接亚洲东北部和阿拉斯加的白令海峡）。

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.

关于这次移民的第一个水路理论是在11000-12000年前，有一片无冰通道，从白令陆桥东部延伸至北美，北部大冰川的南边。

The first water craft theory about this 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.

正是位于两块巨大的冰盖之间的大陆通道（劳伦泰德冰盖东部和科迪勒拉冰盖西部）使得移民可能南迁。

It was this midcontinental corridor between two massive ice sheets—the Laurentide to the east and the Cordilleran to the west—that enabled the southward migration.

当古生态学家格伦麦克唐纳德表示放射性测年法这一最重要的证据是错误的，而这本来是用来证实不冻走廊的证据，无冰通道的理论也开始受到了质疑。

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.

他十分确定的表示，这样的不冻走廊是在更晚一些才出现，那时候大陆冰盖开始最后一次衰退。

He persuasively argued that such an ice-free corridor did not exist until much later, when the continental ice began its final retreat.

另一个理论开始得到更多支持，即早在16000年前，人们可能用了船只，也许是动物皮做的船，从白令陆桥开始沿着阿拉斯加海湾南移，然后沿着北美西北海岸继续南移。

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.

这个路线使得人类在大陆冰川融化之前可以进入美国南部。

This route would have enabled humans to enter southern areas of the Americas prior to the melting of the continental glaciers.

直到1970年早期，大多数考古学家都没考虑过海岸线可能是一条进入美国的移民线路，因为地质学家一开始认为，在冰河世纪时期，整个西北海岸都覆盖着冰川。

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.

人们推测冰层从阿拉斯加/加拿大山区向西延伸到海洋中平坦的大陆架边缘。

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.

这就产生了一个冰川障碍，从阿拉斯加半岛经过阿拉斯加海湾，一直沿着北美西北海岸南移，到我们当今的华盛顿州。

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.

海岸线迁移线路最有影响力的支持者是加拿大考古学家克努特•费莱德马克。

The most influential proponent of the coastal migration route has been Canadian archaeologist Knut Fladmark.

他的理论是通过使用船，人们可以逐渐定居在没有冰川的区域，还有由于海平面降低暴露出来的大陆架。

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.

费莱德马克的假设得到了更多证据：北美语言分支最多的是在美洲西海岸，这表明这个区域最早有人类定居。

Fladmark’s hypothesis received additional support from the fact that the greatest diversity in Native American languages occurs along the west coast of the Americas, suggesting that this region has been settled the longest.

最近的地质研究记录了13000年以前，加拿大英属哥伦比亚主要沿海区域去冰川化和不冻区域的存在。

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.

研究表明沿着内部大陆架的阿拉斯加东南部，一块巨大区域直到上一次冰河世纪末期都没覆盖冰川。

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.

研究表明除了位于英属哥伦比亚西南部和华盛顿州之间的250英里海岸区域，北美西北海岸在16000年之前基本都没有冰川覆盖。

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.

16000年之前，海岸沿线的巨大区域冰川褪去，这可能提供了一个海边通道来让植物、动物和人在13000年至14000年前移动。

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 and14,000 years ago.

海岸线理论在近些年逐渐得到更多支持，因为人们在阿拉斯加东南部发现了诸如北美驯鹿和棕熊等大型动物的遗骸，这些遗骸的年代为距今10000至12500年之间。

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.

大多数科学家认为这一时期并不适合人类生存。

This is the time period in which most scientists formerly believed the area to be inhospitable for humans.

如果当时的环境足够支撑熊的繁殖，那就有足够的食物来提供给人类。

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.

费莱德马克和其它人认为早在14000年前冰河世纪晚期，第一批移民乘船沿着西北部海岸到美洲。

Fladmark and others 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.

最近的地质证据表明人们可能居住在大陆架沿岸的无冰区域，这些区域在13000至14000年之前由于海平面较低而暴露在外。

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 between 13,000 and 14,000 years ago.

海岸线假设表明当时的经济是建立在海洋生物的捕猎，海水中捕鱼，贝壳类生物采集，还有船只的使用之上。

The coastal hypothesis suggests an economy based on marine mammal hunting, saltwater fishing, shellfish gathering, and the use of watercraft.

由于往东有冰川的阻碍，西部是太平洋，北部人口众多，也许人们更愿意向南部迁移。

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.

According to paragraph 1, the theory that people first migrated to the Americas by way of an ice-free corridor was seriously called into question by

The word “persuasively” in the passage is closest in meaning to

Paragraph 2 begins by presenting a theory and then goes on to

Paragraph 2 supports the idea that, before the 1970s, most archaeologists held which of the following views about the earliest people to reach the Americas?

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

The author’s purpose in paragraph 4 is to

According to paragraph 5, the discovery of the remains of large land animals supports the coastal hypothesis by providing evidence that

According to paragraph 5, the most recent geologic research provides support for a first colonization of America dating as far back as

Look at the four squares  that indicate where the following sentence could be added to the passage. Moreover, other evidence suggests that even if an ice-free corridor did exist, it would have lacked the resources needed for human colonization.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Colonizing the Americas via the Northwest Coast 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 this 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 this midcontinental corridor between two massive ice sheets—the Laurentide to the east and the Cordilleran 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 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 from the fact that the greatest diversity 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 others 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 between 13,000 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.