During thepeakof the last ice age, northeast Asia (Siberia) and Alaska were connected by abroadlandmasscalled the Bering Land Bridge. This land bridge existed because so much of Earth’s water was frozen in the great ice sheets that sea levels were over 100 meterslowerthan they are today. Between 25,000 and 10,000 years ago, Siberia, the Bering Land Bridge, and Alaska shared manyenvironmentalcharacteristics. These included acommonmammalianfaunaof large mammals, acommonfloracomposed ofbroadgrasslands as well as wind-swept dunes andtundra, and acommonclimatewith cold, dry winters andsomewhatwarmer summers. Therecognitionthat many aspects of the modernfloraandfaunawere present on both sides of the Bering Sea asremnantsof the ice-agelandscapeled to thisregionbeing named Beringia.

It isthroughBeringia that small groups of largemammalhunters, slowly expanding their hunting territories,eventuallycolonized North and South America. On this archaeologists generally agree, but that is where the agreement stops. Onebroadarea of disagreement in explaining the peopling of the Americas is thedomainof paleoecologists, but it iscriticalto understanding human history: what was Beringia like?

The Beringianlandscapewas very different from what it is today. Broad,windsweptvalleys;glaciatedmountains;sparsevegetation; and lessmoisturecreated a rather forbidding landmass. This landmasssupported herds of now-extinctspeciesofmammoth, bison, and horse andsomewhatmodern versions ofcaribou, musk ox, elk, and saigaantelope. These grazers supported in turn a number ofimpressivecarnivores, including thegiantshort-facedbear, the saber-tooth cat, and a largespeciesof lion.

The presence ofmammalspeciesthatrequiregrasslandvegetationhas ledArcticbiologist Dale Guthrie toarguethat while cold and dry, there must have beenbroadareas ofdensevegetationto support herds ofmammoth, horse, and bison. Further, nearly all of the ice-agefaunahad teeth thatindicateanadaptationto grasses and sedges; they could not have been supported by a modernfloraof mosses and lichens. Guthrie has also demonstrated that thelandscapemust have beensubjecttointenseandcontinuouswinds, especially in winter. He makes thisargumentbased on theanatomyof horse and bison, which do not have the ability to search for foodthroughdeep snow cover. They need landscapes with strong winds that remove the winter snows, exposing the dry grassesbeneath. Guthrie applied theterm“mammothsteppe" tocharacterizethislandscape.

Incontrast, Paul Colinvaux has offered a counterargument based on theanalysisofpollenin lake sediments dating to the last ice age. He found that the amount ofpollenrecovered in these sediments is so low that the Beringianlandscapeduring thepeakof the lastglaciationwas more likely to have been what he termed a "polardesert," with little or onlysparsevegetation, in no way was it possible that thisregioncould have supported large herds of mammals and thus, human hunters. Guthrie has argued against this view by pointing out thatradiocarbonanalysisofmammoth, horse, and bison bones from Beringian deposits revealed that the bonesdateto the period of mostintenseglaciation.

Theargumentseemed to be at a standstill until a number of recent studies resulted in aspectacularsuite of new finds. The first was the discovery of a 1,000-square-kilometer preservedpatchof Beringianvegetationdating to just over 17,000 years ago—thepeakof the last ice age. The plants were preserved under a thick ash fall from avolcaniceruption. Investigations of the plants found grasses, sedges, mosses, and many other varieties in a nearlycontinuouscover, as was predicted by Guthrie. But thisvegetationhad a thinrootmatwith no soilformation, demonstrating that there was little long-termstabilityin plant cover, a finding supporting some of the arguments of Colinvaux. A mixture ofcontinuousbut thinvegetationsupporting herds of large mammals is one that seemsplausibleandrealisticwith theavailabledata.

Questions:
question_stem: The word "remnants" in the passage is closest in meaning to
choices: tag: A
text: remains

tag: B
text: evidence

tag: C
text: results

tag: D
text: reminders
answer_key: A
explanation: 【题目翻译】文章中“remnants”一词的意思最接近于以下哪个选项？
A 残余、遗骸
B 证据
C 结果
D 提醒

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“remnants”,定位到原句“he recognition that many aspects of the modern flora and fauna were present on both sides of the Bering Sea as remnants of the ice-age landscape led to this region being named Beringia.
”。
【词汇解析】：词汇“remnants”的意思是“残余、残留”,带入到原句中，原句的意思是“他认识到现代动植物的许多方面都存在于白令海两侧，作为冰河时代景观的遗迹，导致这个地区被命名为贝林吉亚。”。

【选项分析】
A 残余、遗骸。同义替换，正确
B 证据。不符，错误
C 结果。不符，错误
D 提醒。不符，错误

question_stem: The word "domain" in the passage is closest in meaning to
choices: tag: A
text: field of expertise

tag: B
text: challenge

tag: C
text: interest

tag: D
text: responsibility
answer_key: A
explanation: 【题目翻译】文章中“domain”一词的意思最接近于
A：专业领域
B：挑战
C：兴趣
D：责任

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“domain”,定位到原句“One broad area of disagreement in explaining the peopling of the Americas is the domain of paleoecologists, but it is critical to understanding human history: what was Beringia like?”
4、【词汇解析】：词汇“domain”的意思是“领域”,带入到原句中，原句的意思是“在解释美洲的人口问题上，一个广泛的分歧领域是古生态学家的领域，但是理解人类历史却是至关重要的：贝林吉亚是什么样的？”

【选项分析】
A：专业领域。同义替换，正确
B：挑战。不符，错误
C：兴趣。不符，错误
D：责任。不符，错误

question_stem: According to paragraph 3, all of the following are true of the Beringian landscape EXCEPT.
choices: tag: A
text: There was little vegetation.

tag: B
text: The mammal species there all survived into modern versions.

tag: C
text: The climate was drier than it is today.

tag: D
text: There were mountains with glaciers.
answer_key: B
explanation: 【题目翻译】根据第3段，关于贝林根风景区，以下所有情况均属实除了哪一项？
A：几乎没有植被。

B：那里的哺乳动物物种都存活到现代版本中。

C：气候比今天干燥。

D：那儿有山有冰川。

【判定题型】：根据题干中出现的大写“EXCEPT”/"NOT" 等其他明显表示否定的词，可以判定本题为否定事实信息题，需要找出与原文信息不符的那个答案。

【关键词定位】根据题干关键词 the Beringian landscape 可以将出题范围锁定在 Passage 3。

【选项分析】
A 选项对应原文的 sparse vegetation. 正确
B 选项的 all 过于绝对，与原文的 This land mass supported… and somewhat modern versions of caribou…中的 somewhat 的表述不符。 错误
C 选项对应原文的 They need landscapes with strong winds that remove the winter snows, exposing the dry grasses beneath. 正确
D 选项是原文 glaciated mountains 的同义替换。正确

question_stem: The purpose of paragraph 3 is to
choices: tag: A
text: contrast today’s Beringian landscape with other landscapes in the American continent

tag: B
text: describe the Beringian landscape during the last ice age

tag: C
text: explain why so many Beringian species became extinct during the last ice age

tag: D
text: summarize the information about Beringia that historians agree on
answer_key: B
explanation: 【题目翻译】第3段的目的是什么？
A：今天的贝林根山水与美洲大陆的其他山水形成对比。

B：描述一下上次冰河时代贝林根的风景。

C：解释为什么这么多贝林根物种在上个冰河时期灭绝？

D：总结历史学家一致同意的有关贝林吉亚的信息

【判定题型】：根据题目问法，题目询问第三段的组成或构成方式/段落与段落的关系/某一段在全文中所起的作用，故判断本题为组织结构题。

【内容分析】第3段主要就是描述 last ice age 期间的 Beringian 的景色。

【选项分析】
A 选项的 contrast 原文没有提到。错误
B 选项符合文意。正确
C 选项的 explain 的内容原文没有提到。错误
D 选项并没有对 historians 所同义的 information 进行 summarize。错误

question_stem: The word "continuous" in the passage is closest in meaning to
choices: tag: A
text: unpredictable

tag: B
text: very cold

tag: C
text: dangerous

tag: D
text: uninterrupted
answer_key: D
explanation: 【题目翻译】文章中“continuous”一词的意思最接近于
A 不可预测的
B 很冷的
C 危险的
D 连续的，不间断的

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“continuous”,定位到原句 A mixture of continuous but thin vegetation supporting herds of large mammals is one that seems plausible and realistic with the available data.
”。

【词汇解析】：词汇“continuous”的意思是“持续的”,带入到原句中，原句的意思是“由连续而薄的植被支撑的大型哺乳动物群组成的混合体，根据现有数据，似乎是合理和现实的”。

【选项分析】
A 不可预测的。不符，错误
B 很冷的。不符，错误
C 危险的。不符，错误
D 连续的，不间断的。同义替换，正确

question_stem: 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.
choices: tag: A
text: According to biologist Dale Guthrie, mammal species require broad areas of vegetation to survive.

tag: B
text: Dale Guthrie is an Arctic biologist who argued that broad areas of dense vegetation were surely enough to attract mammals such as mammoth, horse, and bison to Beringia.

tag: C
text: Dale Guthrie argued that Beringia, though cold and dry, must have had enough dense vegetation to support the herds of mammoth, horse, and bison that lived there.

tag: D
text: As long as Beringia was cold and dry, argued Dale Guthrie, dense vegetation grew in order to support the herds of mammoth, horse, and bison—the mammal species present there.
answer_key: C
explanation: 【题目翻译】下面哪句话最能表达文章中突出显示的句子中的基本信息？不正确的选择会以重要方式改变含义，或者漏掉必要的信息。
A：根据生物学家戴尔·古思里的说法，哺乳动物需要大面积的植被才能生存。

B：戴尔·古思里是一位北极生物学家，他认为大片茂密的植被肯定足以吸引猛犸象、马和野牛等哺乳动物来到白令江。

C：戴尔·古思里认为，白令吉亚虽然寒冷干燥，但一定有足够茂密的植被来养活生活在那里的猛犸象、马和野牛群。

D：戴尔·古思里认为，只要白令吉亚是寒冷干燥的，茂密的植被就会生长起来，以支持存在于那里的猛犸象、马和野牛群。

【判定题型】：根据题目问法，题目要求选择和高亮句意思逻辑都最为接近的句子，故判断本题为句子简化题。

【句子分析】原句的逻辑 while 表示让步，句子核心：哺乳动物的存在让 Dale 认为即使很冷也很干燥, 也一定植被去支持哺育那些哺乳动物。

【选项分析】
A：不是需要大面积的植被，而是肯定会有植被。故错误。
B：不是“吸引”，而是去“哺育”。B 选项的关键词错了。故错误。
C：符合文意，正确。句子对应原句的两个核心，though 的逻辑关系正确，因此 C 选项正确。
D：植被的生长并不是因为的天气的寒冷干燥，2者并无直接联系。故错误。

question_stem: According to paragraph 4, Guthrie believes that the teeth of ice-age fauna support which of the following conclusions?
choices: tag: A
text: Large mammals would not have been able to survive in the Beringian landscape.

tag: B
text: Grasslands were part of the Beringian landscape.

tag: C
text: Strong winds exposed dry grasses under the snow.

tag: D
text: Horses and bison did not have the ability to search for food through deep snow cover.
answer_key: B
explanation: 【题目翻译】根据第4段，Guthrie 认为冰河期动物群的牙齿支持以下哪个结论？
A：大型哺乳动物不可能在贝林根群岛上生存。

B:草地是贝林根群岛景观的一部分。

C:强风把干草吹到雪地里。

D：马和野牛没有能力在深厚的积雪中寻找食物。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】此题根据关键词 teeth, ice-age fauna 定位到原文的 nearly all of the ice-age fauna had teeth that indicate an adaptation to grasses and sedges.意思是“几乎所有的冰河期动物都有表明对草和莎草适应的牙齿。”

【逻辑分析】第四段表明了几乎所有冰河时代动物的牙齿都表明它们适应了禾草和莎草。

【选项分析】
A：不符，错误。文章没有提到。
B：符合，正确。此句中的 indicate 对应题干的 support, B 选项的 grassland 对应句中的 an adaptation to grasses and sedges。故 B 选项正确。
C：不符，错误。文章说的是吹走积雪，露出干草。
D：不符，错误。文章中说是有能力的。

question_stem: According to paragraph 4, which of the following statements is true of the relationship between ice-age Benngian animals and their environment?
choices: tag: A
text: When present in sufficient quantities, lichens and mosses provide enough nutrients to satisfy the needs of herds of large mammals.

tag: B
text: The anatomy of certain animals present in that environment provides information about the intensity of winds there at that time.

tag: C
text: The structure of the teeth of most ice-age fauna indicates that they preyed on animals such as the mammoth, horse, and bison.

tag: D
text: Horses and bison are large enough that their feet can easily penetrate deep snow and uncover areas where they can feed on plant material.
answer_key: B
explanation: 【题目翻译】根据第4段，下列哪一项关于冰河期 Benngian 动物与环境之间的关系的说法是正确的？
A：当苔藓和苔藓数量足够时，它们能提供足够的营养以满足大型哺乳动物群的需要。

B：在那个环境中存在的某些动物的解剖学提供了当时那里的风强度的信息。

C：大多数冰河期动物的牙齿结构表明它们捕食猛犸、马和野牛等动物。

D：马和野牛足够大，它们的脚可以轻易地穿透厚厚的积雪，发现它们可以吃植物材料的地方。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】直接根据选项找关键词，对应文章。

【逻辑分析】第四段描述了哺乳动物和草地植被之间的关系，和生物学家戴尔•古思莱的观点。

【选项分析】
A 选项的表述与原文 They could not have been supported by a modern flora of mosses and lichens 的表述不符。
B 选项对应原文的 Guthrie has…the landscape must have been subject to intense and continuous winds, …through deep snow cover. 
C 选项对应原文的…ice-age fauna had teeth that indicate…,但是选项中 indicates 的内容与原文不符。
D 选项的 large enough… feet can easily penetrate 的表述与原文 do not have the ability…的表述不符，错误

question_stem: In paragraph 5, the amount of pollen in Beringian lake sediments from the last ice age is used to explain
choices: tag: A
text: how long the ice age lasted

tag: B
text: how important pollen is as a source of food

tag: C
text: how many different kinds of plants produce pollen

tag: D
text: how little vegetation must have been present at that time
answer_key: D
explanation: 【题目翻译】在第5段中，末次冰河时代贝林根湖沉积物中的花粉量用来解释什么？
A 冰河时代持续了多久？

B 花粉作为食物来源有多重要？

C 有多少种不同的植物产生花粉？

D 那时候植被一定很少了。

【判定题型】：根据题干问法“……explain”，题目询问第五段的修辞目的，可以判断本题为修辞目的题。

【关键词定位】：根据关键词“pollen”,定位到 Passage 5第1句，原句为“In contrast, Paul Colinvaux has offered a counterargument based on the analysis of pollen in lake sediments dating to the last ice age.”。

【引用内容分析】根据原文第5段可知，Paul Colinvaux 对 pollen 的含量做出分析的原因就是为了说明在 last ice age 时期，植被是非常少的。

【选项分析】
A：不符，错误
B：不符，错误
C：不符，错误
D：符合，正确

question_stem: According to paragraph 5, how did Dale Guthrie use the information about radiocarbon analysis of bones fromBeringian deposits?
choices: tag: A
text: To suggest that Colinvaux should have used different methods to measure the amount of pollen in ice-age lake sediments

tag: B
text: To argue that the large Beringian mammals must have eaten plants that produce little, if any, pollen

tag: C
text: To show that the conclusions that Colinvaux drew from the analysis of pollen in ice-age lake sediments cannot be correct

tag: D
text: To explain why so-called polar deserts are incapable of supporting such large animals as mammoth, horse, and bison
answer_key: C
explanation: 【题目翻译】根据第5段，Dale Guthrie 是如何利用来自贝林根沉积物的骨骼的放射性碳分析的信息的？
A：建议 Col.ux 应该用不同的方法测定冰河期湖泊沉积物中的花粉量。

B：认为大型贝林根哺乳动物一定吃了花粉很少的植物，如果有的话。

C：表明从冰河湖沉积物花粉分析中得出的结论是不正确的。

D：解释为什么所谓的极地沙漠不能养活像猛犸、马和野牛这样的大型动物。

【判定题型】：题目问的是文章中的具体细节信息，故根据题目问法可以判断本题为事实信息题。

【关键词定位】：根据关键词“adiocarbon analysis”,定位到 Passage 5 ，原句为“Guthrie has argued against this view by pointing out that radiocarbon analysis of mammoth, horse, and bison bones from Beringian deposits revealed that the bones date to the period of most intense glaciation.”，意思是“Guthrie 反对这种观点，他指出，对来自贝林根矿床的猛犸、马和野牛骨骼的放射性碳分析显示，这些骨骼可以追溯到最强烈的冰川作用时期。”。

【逻辑分析】根据原文，Dale Guthrie 是反对 Paul Colinvaux 所得出的这个地区不可能养活一大群哺乳动物这个结论。因为 Dale Guthrie 从对一些动物的放射性的分析中发现：mammoth, horse and bison bones 是确实存在于 intense glaciation 时期的，也就是他认为 Paul Colinvaux 的结论是错误的。

【选项分析】
A：未提到不同方法，故错误。
B：文章没有直接提到哺乳动物和花粉少得植物的直接关系。故错误。
C：符合文意，正确。
D：没有做解释，而是提出了他自己的论点。故错误。

question_stem: The word "plausible" in the passage is closest in meaning to
choices: tag: A
text: preferable

tag: B
text: practical

tag: C
text: reasonable

tag: D
text: advantageous
answer_key: C
explanation: 【题目翻译】文章中“plausible”这个词的意思最接近于
A 更可取的
B 实际的
C 合理的
D 有优势的

【判定题型】：题目要求选出与高亮单词意思最接近的选项，故判断本题为词汇题。

【关键词定位】：根据关键词“plausible”,定位到原句“A mixture of continuous but thin vegetation supporting herds of large mammals is one that seems plausible and realistic with the available data.”。

【词汇解析】：词汇“plausible”的意思是“似是而非的”,带入到原句中，原句的意思是“由连续而薄的植被支撑的大型哺乳动物群组成的混合体，根据现有数据，似乎是合理和现实的。”。

【选项分析】
A 更可取的。不符，错误
B 实际的。不符，错误
C 合理的。符合，正确
D 有优势的。不符，错误

question_stem: Which of the following best describes the organization of paragraph 6?
choices: tag: A
text: Two contrasting views are presented, and a study that could decide between them is proposed

tag: B
text: An argument is offered, and reasons both for and against the argument are presented

tag: C
text: A claim is made, and a study supporting the claim is described

tag: D
text: New information is presented, and the information is used to show that two competing explanations can each be seen as correct in some way.
answer_key: D
explanation: 【题目翻译】下面最好地描述了第6段的结构。

A：提出了两种截然不同的观点，并提出了一种能决定这两种观点的研究。

B：提出了论点，并且给出了支持和反对论点的理由。

C：提出看法，并描述支持这个看法的研究。

D：给出了新的信息，并用这些信息表明两种相互竞争的解释在某种程度上可以被认为是正确的。

【判定题型】：根据题目问法，题目询问 xxx 组成或构成方式/段落与段落的关系/某一段在全文中所起的作用，故判断本题为组织结构题。

【内容分析】第6段先明确说最近的研究产生了新的发现，然后又说 the first… as was predicted by Guthrie. 即说明此发现是与 Guthrie 的观点吻合。之后又说 But…, a finding supporting some of the arguments of Colinvaux.也就是说此发现也说明 Colinvaux 的部分观点也是对的。

【选项分析】
A：不符，错误。段落只提出了一种新观点。
B：不符，错误。没有提出任何理由，只是在叙述发现。
C：不符，错误。没有提出研究。
D：符合，正确。文章提出新的发现，并证明其实正确的。