托福Tpo33阅读详细解释

The First Civilizations

Paragraph 1

Evidence suggests that an important stimulus behind the rise of early

civilizations was the development of settled agriculture, which unleashed a series of changes in the organization of human communities that culminated in the rise of large ancient empires.

1. The phrase “culminated in” in the passage is closest in meaning to

A. reached a high point with

B. logically followed from

C. partly contributed to

D. marked

答案 A

解析词汇题: culminate, 达到顶点/高潮, 对应A 选项: 达到高点。Paragraph 2

The exact time and place that crops were first cultivated successfully is uncertain. Many prehistorians believe that farming may have emerged in dependently in several different areas of the world when small communities, driven by increasing population and a decline in available food resources, began to plant seeds in the ground in an effort to guarantee their survival. The first farmers, who may have lived as long as

10,000 years ago, undoubtedly used simple techniques and still relied primarily on other forms of food production, such as hunting, foraging, or pastoralism. The real breakthrough took place when farmers began to cultivate crops along the floodplains

of river systems. The advantage was that crops grown in such areas were not as dependent on rainfall and therefore produced a more reliable harvest. An additional benefit was that the sediment carried by the river waters deposited nutrients in the soil, thus enabling the farmer to cultivate a single plot of ground for many years without moving to a new location. Thus, the first truly sedentary (that is, nonmigratory) societies were born. As time went on, such communities gradually learned how to direct the flow of water to enhance the productive capacity of the land, while the introduction of the iron plow eventually led to the cultivation of heavy soils not previously susceptible to agriculture.

2. In paragraph 2, which of the following statements is true of early farmers?

A. They used farming to supplement other food sources.

B. They were driven out of small communities.

C. They were victims of flooding.

D. They farmed several plots of land at once.

答案 A

解析细节题: 定位句Many prehistorians believe that farming may have emerged independently in several different areas of the world when small communities, driven by increasing population and a decline in available food resources, began to plant seeds in the ground in an effort to guarantee their survival. 意思是当食物来源短缺的时候来时种植粮食来维持生计，对应 A

选项: 他们用农业来补充其他食物来源。

3. The word “undoubtedly” in the passage is closest in meaning to

A. increasingly

B. certainly

C. in general

D. apparently

答案 B

解析词汇题: undoubtedly 毫无疑问地, 对应 B 选项: 理所应当地。

4. According to paragraph 2, what are TWO reasons why farmers chose river valleys for cultivation? To receive credit you must select TWO answer choices.

A. The soils in river valleys were rich in nutrients.

B. The crops grown in river valleys were not completely dependent on rainwater.

C. Farming techniques could not be easily applied to soils far from rivers.

D. The heavier weight of river soil resulted in more reliable harvests.

答案AB

解析细节题: 定位句The advantage was that crops grown in such areas were not as dependent on rainfall and therefore produced a more reliable harvest. An

additional benefit was that the sediment carried by the river waters deposited nutrients in the soil, thus enabling the farmer to cultivate a single plot of ground

for many years without moving to a new location. 里面提到了not as

dependent on rainfall, 不太依赖于降雨, 对应B 选项: 不完全依赖降水。同

时也提到了deposited nutrients in the soil, 在土壤中沉淀营养, 对应 A 选项:

土壤营养丰富。

5. The word “enhance” in the passage is closest in meaning to

A. serve

B. improve

C. control

D. protect

答案 B

解析词汇题: enhance, 提高, 增强, 对应B 选项, 提高, 改善。Paragraph 3

The spread of this river valley agriculture in various parts of Asia and Africa was the decisive factor in the rise of the first civilizations. The increase in food production in these regions led to a significant growth in population, while efforts to control the

flow of water to maximize the irrigation of cultivated areas and to protect the local inhabitants from hostile forces outside the community provoked the first steps toward cooperative activities on a large scale. The need to oversee the entire process brought about the emergence of an elite that was eventually transformed into a government.

6. The word “provoked” in the passage i s closest in meaning to

A. secured

B. coordinated

C. modeled

D. brought about

答案 D

解析词汇题: provoke 激起, 引起, 招致, 激怒, 对应D 选项, 引起。

7. According to paragraph 3, which of the following is NOT a reason why

governments first arose among agricultural communities?

A. A significant increase in population

B. The desire to control water resources for irrigation

C. The need for protection from outside forces

D. The demand for organized communication with other communities

答案 D

解析否定细节题: 定位第二句The increase in food production in these regions led to a significant growth in population, while efforts to control the flow of water

to maximize the irrigation of cultivated areas and to protect the local inhabitants

from hostile forces outside the community provoked the first steps toward cooperative activities on a large scale. 中的significant growth in population

对应A 选项; efforts to control the flow of water 对应B 选项; protect the local inhabitants from hostile forces outside the community 对应C 选项。因此D 选

项错误。

Paragraph 4

The first clear steps in the rise of the first civilizations took place in the fourth and

third millennia B.C. in Mesopotamia, northern Africa, India, and China. How the first governments took shape in these areas is not certain, but anthropologists studying the evolution of human communities in various parts of the world have discovered that one common stage in the process is the emergence of what are called “big men” within a single village or a collection of villages. By means of their military prowess, dominant personalities, or political talents, these people gradually emerge as the leaders of that community. In time, the “big men” become formal symbols of authority and pass on that authority to others within their own family. As the communities continue to grow in size and material wealth, the “big men” assume hereditary status, and their allies and family members are transformed into a hereditary monarchy.

8. According to paragraph 4, what is not known about the rise of the first …civilizations?

A. Where the first steps toward civilization took place

B. Who was allowed to replace “big men” after the “big men” died

C. Why some individuals became recognized as leaders

D. How governments emerged

答案 D

解析否定细节题: 定位句The first clear steps in the rise of the first civilizations took place in the fourth and third millennia B.C. in Mesopotamia, northern

Africa, India, and China. 出现地点northern Africa, India and China 对应A 选

项。定位句As the communities continue to grow in size and material wealth,

the “big men”assume hereditary status, 提到了世袭制, 对应B 选项。定位句By means of their military prowess, dominant personalities, or political talents,

these people gradually emerge as the leaders of that community. 对应C 选项。

定位句How the first governments took shape in these areas is not certain. 与 D

选项相违背, 因此D 选项错误。

9. What is the relationship between paragraphs 3 and 4 in the passage?

A. Paragraph 3 explains why a need for leadership arose in early civilizations,

and paragraph 4 describes how that leadership developed.

B. Paragraph 3 suggests that agriculture was first practiced in Asia and Africa,

and paragraph 4 discusses how it might have later spread to the rest of the

world.

C. Paragraph 3 describes several methods of early government, and paragraph 4 gives an extended example of one of them.

D. Paragraph 3 discusses a cause of the spread of river valley agriculture in early civilizations, and paragraph 4 discusses an effect.

答案 A

解析宏观题: 第三段主要是说领导者即后来政府形成的原因, 第四段主要是讲

领导者是如何形成的。对应 A 中why 和how。

Paragraph 5

The appearance of these sedentary societies had a major impact on the social organizations, religious beliefs, and way of life of the peoples living within their boundaries.■With the increase in population and the development of centralized authority came the emergence of the cities.■While some of these urban centers were identified with a particular economic function, such as proximity to gold or iron

deposits or a strategic location on a major trade route, others served primarily as administrative centers or the site of temples for the official cult or other ritual observances.■Within these cities, new forms of livelihood appeared to satisfy the growing need for social services and consumer goods.■Some people became artisans

or merchants, while others became warriors, scholars, or priests. In some cases, the physical division within the first cities reflected the strict hierarchical character of the society as a whole, with a royal palace surrounded by an imposing wall and separate

from the remainder of the urban population. In other instances, such as the Indus

River Valley, the cities lacked a royal precinct and the ostentatious palaces that

marked their contemporaries elsewhere.

10. 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.

A. Some cities were associated with economic activities, while others were government or religious centers.

B. Emerging cities generally served strategic administrative, economic, and

religious purposes.

C. The creation of an economic or administrative activity led to the emergence

of a city for its proper supervision.

D. Some cities emerged as economic centers and later became the sites of administrative or religious activities.

答案 A

解析句子简化题: 原句逻辑while 表示对比转折; 句子核心: 城市中心的经济功能以及管理中心的仪式功能。A 选项句子对应两个核心, while 的转折对比

关系正确, 因此 A 选项正确。

11. Paragraph 5 suggests that which of the following was a consequence of the

emergence of cities?

A. The decentralization of authority

B. An increase in religious activity

C. The emergence of service- and production-related jobs

D. A decreased reliance on mineral resources

答案 C

解析推断题: 定位句Within these cities, new forms of livelihood appeared to satisfy the growing need for social services and consumer goods. 在这些城市

只能给, 新的生活形式的出现满足了不断增长的社会服务和消费品的需

求。

可以推断出有需求就有供给, 就会出现与之相关的产业。

12. According to paragraph 5, why were huge walls built around early royal palaces?

A. To protect the inhabitants from invaders

B. To mark the urban areas

C. To separate the ruling class from the rest of the population

D. To represent the prosperity of a city

答案 C

解析细节题: 定位句In some cases, the physical division within the first cities reflected the strict hierarchical character of the society as a whole, with a royal palace surrounded by an imposing wall and separate from the remainder of the urban population. 意思是说通过建立高墙来建立严格的等级制度, 将统治

者和普通老板姓区分开来, 对应C 选项。

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

This was accompanied by increased professional specialization.

Where would the sentence best fit? Click on a square to add the sentence to the passage.

答案: 第四个方框

解析: 句子插入题This was accompanied by increased professional specialization 中的professional specialization 职业专门化对应第四个方框之后句子中的

artisans or merchants, warriors, scholars, or priests。

14. 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.

The practice of settled agriculture in some areas of Asia and Africa was

crucial to the development of early civilizations.

Answer Choices:

A. Prehistorians disagree as to whether early farmers first cultivated crops along floodplains or first tried cultivating crops in less successful environments.

错。定位第二段: 没有出现disagree, less successful environments 的相关概念。

B. Cultivation in fertile river valleys resulted in predictable harvests, which meant that farmers no longer needed to migrate constantly in search of food.

正确。对应第二段An additional benefit was that the sediment carried by the river waters deposited nutrients in the soil, thus enabling the farmer to cultivate a

single plot of ground for many years without moving to a new location. Thus,

the first truly sedentary (that is, nonmigratory) societies were born.因为土壤

中含有丰富的营养, 所以一块地农民可以种很多年, 因此就不用迁移到别

的地方, 最后就定居了。

C. Because crops could be cultivated more successfully where farmers were not completely dependent on rainfall, hostilities between groups arose over control of

the river systems.

错。定位第二, 三段。The advantage was that crops grown in such areas were not as dependent on rainfall and therefore produced a more reliable harvest. The

increase in food production in these regions led to a significant growth in population, while efforts to control the flow of water to maximize the irrigation

of cultivated areas and to protect the local inhabitants from hostile forces outside

the community provoked the first steps toward cooperative activities on a large scale. 原句是转折关系, 不是因果关系。

D. The need to organize the effort to ensure the food supply and defend the land led to the formation of elite supervising groups that eventually became the first governments.

正确。对应第三段的核心主旨: 政府的形成。

E. Increasingly centralized forms of administration resulted in the emergence of social classes and in the development of cities as trade, administration, or religious centers.

正确。对应第五段核心意思: 中央集权导致了社会阶层和不同功能城市的形成。

F. Unlike other early civilizations, those that developed in the Indus River Valley did

not have any spectacular palaces or areas for exclusive use by the authorities.

错。定位第五段: In other instances, such as the Indus River Valley, the cities lacked a royal precinct and the ostentatious palaces that marked their contemporaries elsewhere. 意思是说Indus River Valley 这个地方没有华丽的宫殿来代表权

力。

虽然F 选项没有什么太大的错误, 但它属于段落细节, 可以参照E 选项正确

的原因。

答案：BDE

Railroads and Commercial Agriculture in Nineteenth-Century United States Paragraph 1

By 1850 the United States possessed roughly 9,000 miles of railroad track; then years later it had over 30,000 miles, more than the rest of the world combined. Much of the new construction during the 1850s occurred west of the Appalachian Mountains E over 2,000 miles in the states of Ohio and Illinois alone.

1. According to paragraph 1, each of the following is true about railroad track in the United States EXCEPT:

A. In 1850 the United States had less than 10,000 miles of railroad track.

B. By the end of the 1850s, Ohio and Illinois contained more railroad track than any other state in the country.

C. Much of the railroad track built in the United States during the 1850s was located west of the Appalachian Mountain.

D. By 1860 there were more miles of railroad track in the United States than in

any other country.

答案 B

解析否定细节题: 定位句By 1850 the United States possessed roughly 9,000 miles of railroad track; 对应A 选项。定位句Much of the new construction during

the 1850s occurred west of the Appalachian Mountains E over 2,000 miles in

the states of Ohio and Illinois alone. 对应C 选项, 同时由于该句子中没有出

现有关Ohio and Illinois 比较的相关信息, 因此 B 选项错误。定位句then years later it had over 30,000 miles, more than the rest of the world combined.

对应D 选项。

Paragraph2

The effect of the new railroad lines rippled outward through the economy. Farmers along the tracks began to specialize in corps that they could market in distant locations. With their profits they purchased manufactured goods that earlier they might have made at home. Before the railroad reached Tennessee, the state produced about 25,000 bushels (or 640 tons) of wheat, which sold for less than 50 cents a bushel. Once the railroad came, farmers in the same counties grew 400,000 bushels (over 10,000 tons) and sold their crop at a dollar a bushel.

2. It can be inferred from paragraph 2 that the new railroads had which of the following effects on farm communities?

A. Most new farms were located along the tracks.

B. Farmers began to grow wheat as a commercial corp.

C. Many famer decided to grow a wider variety of crops.

D. Demand for manufactured goods increased among farmers.

答案 D

解析推断题: 定位句The effect of the new railroad lines rippled outward through the economy. Farmers along the tracks began to specialize in corps that they

could market in distant locations. With their profits they purchased

manufactured goods that earlier they might have made at home. 意思是说因为

铁路建设带动了经济, 农民开始有钱了, 于是就开始买手工制品了。因此就

可以推断出, 农民有钱了就有了买东西的欲望和需求。

Paragraph 3

The new railroad networks shifted the direction of western trade. In 1840 most northwestern grain was shipped south down the Mississippi River to the bustling port

of New Orleans. But low water made steamboat travel hazardous in summer, and ice shut down traffic in winter. Products such as lard, tallow, and cheese quickly spoiled if stored in New Orleans? hot and humid warehouses. Increasingly, traffic from the Midwest flowed west to east, over the new rail lines. Chicago became the region?s hub, linking the farms of the upper Midwest to New York and other eastern cities by more than 2,000 miles of track in 1855. Thus while the value of goods shipped by

river to New Orleans continued to increase, the South?s overall share of western trade dropped dramatically.

3. The word “bustling” in the passage is closest in meaning to

A. famous

B. important

C. growing

D. busy

答案 D

解析词汇题: bustling, 繁忙的, 熙熙攘攘的, 对应 D 选项, 忙碌的。

4. According to paragraph 3, in what way did the new rail networks change western trade?

A. Northwestern farmers almost completely stopped shipping goods by steamboat.

B. Many western goods began to be shipped east by way of Chicago rather than south to New Orleans.

C. Chicago largely replaced New York and other eastern cities as the final market for good for the West.

D. The value of goods shipped west soon became greater than the value of good shipped east.

答案 B

解析细节题: 定位句The new railroad networks shifted the direction of western trade. Chicago became the region?s hub, linking the farms of the upper Midwest

to New York and other eastern cities by more than 2,000 miles of track in 1855.

意思是铁路的建设转移了西方贸易的方向, 芝加哥成为了贸易中心, 取代

了原先的新奥尔良。因此答案是B

5. According to paragraph 3, what was a disadvantage of shipping goods from northwestern areas to New Orleans?

A. There was no reliable way to get goods from New Orleans to eastern cities.

B. The cost of shipping goods by river to New Orleans continued to increase.

C. Goods shipped from New Orleans? neighboring areas had a significant competitive advantage because of their lower transportation costs.

D. The temperatures and humidity.

答案 B

解析细节题: Thus while the value of goods shipped by river to New Orleans continued to increase, the South?s overall share of western trade dropped dramatically. 意思是说因为虽然货物本身的价值在增加, 但是南部的市场

份额却在下降, 就暗示了越来越少人的人愿意通过该途径运货, 即要么速

度太慢要么成本太高。因此这道题的答案是B。

Paragraph4

A sharp rise in demand for grain abroad also encouraged farmers in the Northeast and Midwest to become more commercially oriented. Wheat, which in 1845 commanded $1.08 a bushel in New York City, fetched $2.46 in 1855; in similar fashion the price of corn nearly doubled. Farmers responded by specializing in cash crops, borrowing to purchase more land, and investing in equipment to increase productivity.

6. Paragraph 4 supports the idea that the price of wheat more than doubled between 1845 and 1855 because

A. the price of corn nearly doubled during that same period

B. demand for grain increased sharply outside the United States

C. farmers in the Northeast and Midwest began to specialize in cash crops

D. many farmers had borrowed heavily to purchase land and equipment for raising wheat

答案 B

解析细节题: 定位句A sharp rise in demand for grain abroad also encouraged farmers in the Northeast and Midwest to become more commercially oriented.

国外的粮食需求猛增, 然后该段最后出现的结果就是价格上升。

Paragraph 5

As railroad lines fanned out from Chicago, farmers began to acquire open prairie land in Illinois and then lowa, putting the fertile, deep black soil into production. Commercial agriculture transformed this remarkable treeless environment. To settlers accustomed to eastern woodlands, the thousands of square miles of tall grass were an awesome sight. Indian grass, Canada wild rye, and native big bluestem all grew higher than a person. Because eastern plows could not penetrate the densely tangled roots of prairie grass, the earliest settlers erected farms along the boundary separating the forest from the prairie. In 1837, however, John Deere patented a sharp‐cutting steel plow that sliced through the sod without soil sticking to the blade. Cyrus McCormic refined a mechanical reaper that harvested fourteen times more wheat with the same amount of labor. By the 1850s McCormick was selling 1,000 reapers a year and could not keep up with demand, while Deere turned out 10,000 plows annually.

7. The word “transformed” in the passage is closest in meaning to

A. dominated

B. changed

C. improved

D. created

答案 B

解析词汇题: transform, 变形, 对应B 选项, 改变, 变化。

8. The word “erected” in the passage is closest in meaning to

A. looked for

B. lived on

C. preferred

D. built

答案 D

解析词汇题: erect, 建立, 对应D 选项, 建立, 建造。

9. Why does the author point out that “Indian grass, Canada wild rye, and native big bluestem all grew higher than a person”?

A. to provide a reason why people from the eastern woodlands of the United States were impressed when they saw the prairie

B. to identified an obstacles to the development of the railroad lines fanning out from Chicago

C. to explain why the transformation of the prairies by commercial agriculture was so remarkable

D. to provide evidence supporting the claim that the prairies had fertile, deep

black soil

答案 D

解析修辞目的题: 定位句As railroad lines fanned out from Chicago, farmers began to acquire open prairie land in Illinois and then lowa, putting the fertile, deep

black soil into production. 该段的主旨: 农民将肥沃的黑土投入生产中, 提

干中的信息是一个具体的例子, 表明的是具体的产物。

10. According to paragraph 5, the first settlers generally did not farm open prairie land because

A. they could not plow it effectively with the tools that were available

B. prairie land was usually very expensive to buy

C. the soil along boundaries between the forest and the prairie was more fertile

than the soil of the open prairie

D. the railroad lines had not yet reached the open prairie when the first settlers arrived

答案 A

解析细节题: 定位句Because eastern plows could not penetrate the densely tangled roots of prairie grass, the earliest settlers erected farms along the boundary

separating the forest from the prairie. 原因是犁不能穿透草地, 因此答案只

可能是A。

Paragraph 6

The new commercial farming fundamentally altered the Midwestern landscape and

the environment. Native Americans had grown corn in the region for years, but never

in such large fields as did later settlers who became farmers, whose surpluses were shipped east. Prairie farmers also introduced new crops that were not part of the

earlier ecological system, notably wheat, along with fruits and vegetables.

11. The word “surpluses” in the passage is closest in meaning to

A. extra goods

B. commercial goods

C. unprocessed goods

D. transportable goods

答案 A

解析词汇题: surpluses, 剩余/多余的东西, 对应A 选项extra 额外的, 附加的。Paragraph 7

Native grasses were replaced by a small number of plants cultivated as commodities. Corn had the best yields, but it was primarily used to feed livestock. Because bread played a key role in the American and European diet, wheat became the major cash crop. Tame grasses replaced native grasses in pastures for making hay

Paragraph 8

Western farmers altered the landscape by reducing the annual fires that had kept the prairie free from trees. In the absence of these fires, trees reappeared on land not in cultivation and, if undisturbed, eventually formed woodlots. The earlier unbroken landscape gave to independent farms, each fenced off in a precise checkerboard pattern. It was an artificial ecosystem of animals, woodlots, and crops, whose large,

uniform layout made western farms more efficient than the more‐irregular farms in the East.

12. According to paragraph 8, prairie farmers changed the landscape by doing all of the following EXCEPT:

A. Reducing annual fires

B. Dividing the land into large, regularly‐shaped lots

C. Planting trees that eventually formed woodlots

D. Fencing off their farms

答案 C

解析否定细节题: 定位句Western farmers altered the landscape by reducing the annual fires that had kept the prairie free from trees. 对应A 选项。定位句The earlier unbroken landscape gave to independent farms, each fenced off in a

precise checkerboard pattern. 对应D 选项。定位句The earlier unbroken landscape gave to independent farms, each fenced off in a precise checkerboard pattern. It was an artificial ecosystem of animals, woodlots, and crops, whose

large, uniform layout made western farms more efficient than the more‐

irregular farms in the East. checkerboard pattern 棋盘格样式, 对应 B 选项。C 选项错在没有提到planting trees。

13. Look at the four squares [■] that indicate where the following sentence can be added to the passage. Where would the sentence best fit? Click on a square [■]to insert the sentence in the passage.

Paragraph 3：

The new railroad networks shifted the direction of western trade.■In 1840 most northwestern grain was shipped south down the Mississippi River to the bustling port of New Orleans.■But low water made steamboat travel hazardous in summer, and ice shut down traffic in winter.■Products such as lard, tallow , and cheese quickly spoiled if stored in New Orleans' hot and humid warehouses.■Increasingly, traffic from the Midwest flowed west to east, over the new rail lines. Chicago became the region?s hub, linking the farms of the upper Midwest to New York and other eastern cities by more than 2,000 miles of track in 1855. Thus while the value of goods shipped by

river to New Orleans continued to increase, the South?s overall share of western trade dropped dramatically.

The problems were not limited to routes of transport.

Where would the sentence best fit? Click on a square to add the sentence to the passage.

答案第三个方框

解析句子插入题: 原句的意思是问题不仅局限在道路运输上, 因此我们可以推断出该句子的下一句应该会提到其他的问题, 因此第三个方框满足要求,

前面再讲水路问题, 后面讲到了天气和湿度问题。插入的句子正好起到了

承上启下的作用。

14. 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 answer choices 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 2points.

The huge expansion of rail lines in Midwestern United States during the 1850s

had major economic and environmental effects.

Answer Choices

A. Construction of new rail lines into the Midwest had been effectively stopped by the Appalachian Mountains, but by 1850 improved construction technology had made further advances possible.

错。定位第一段, 没有提到新的铁路建设是被Appalachian Mountains 阻断的。

B. Access to rail lines combined with the development of more‐efficient farming equipment allowed fertile land of the open prairies of the open prairies to be used

for large‐scale commercial agriculture.

正确。对应第二, 五段, 铁路的发展带动经济, 农民获得土地, 改进农作用具, 提高农作物的产量。

C. Rail lines to Chicago and on to the East made it easier to get Midwestern goods to distant markets, while growing demand encouraged crop specialization and led to

higher crop prices.

错。C 选项后半句话正确, 是第4 段的主旨; 但是该选项的的前半句话是第三段

的一个例子, 其主旨应该是该段的首句The new railroad networks shifted the direction of western trade.

D. Reduction of annual prairie fires allowed trees to reappear, and native grasses were replaced by a few commercially grown plants as previously unbroken grasslands

were decided into large fenced fields.

正确。对应第八段主旨, 农民通过各式各样的方法改变地貌, 发展农业。

E. Because of the growing volume of traffic coming by rail from the Northeast and Midwest, the value of goods arriving in New Orleans for shipment to markets

abroad increased dramatically.

正确。对应第三段主要内容The new railroad networks shifted the direction of western trade. Chicago became the region?s hub, linking the farms of the upper Midwest to New York and other eastern cities by more than 2,000 miles of

track in 1855. Thus while the value of goods shipped by river to New Orleans

continued to increase, the South?s overall share of western trade dropped dramatically. 水路交通的没落和铁路运输的兴起繁荣。

F. Native Americans had grown corn on the prairies for years but had not produced

large surpluses because the varieties they planted had far poorer yields than those introduced by commercial farmers.

错。定位第六段, Native Americans had grown corn in the region for years, but never

in such large fields as did later settlers who became farmers, whose surpluses

were shipped east. 只是说明了后来的农民种庄稼产量多; 再结合该段首句,

并没可能和new commercial farming 有关, 但没有提到品种不好。

摘要题

答案BDE

Extinction Episodes of the Past

Paragraph 1

It was not until the Cambrian period, beginning about 600 million years ago, that a

great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. Since the Cambrian period, biodiversity has generally risen, but there have been some notable exceptions. Biodiversity collapsed dramatically during at least five periods because of mass extinctions around the globe. The five major mass extinctions receive most of the attention, but they are only one end of a spectrum of extinction events. Collectively, more species went extinct during smaller events that were less dramatic but more frequent. The best known of the five major extinction events, the one that saw the demise of the dinosaurs, is the Cretaceous-Tertiary extinction.

1. The word “proliferation” i n the passage is closest in meaning to

A. decline

B. extinction

C. increase

D. migration

答案 C

解析proliferation, 繁殖, 激增, 对应C 选项, 增加。

2. Paragraph 1 supports which of the following statements about life on Earth

before the Cambrian period?

A. Biodiversity levels were steady, as indicated by the fossil record.

B. Levels of biodiversity could not be tracked.

C. The most dramatic extinction episode occurred.

D. Few microscopic species existed.

答案 B

解析推断题: 定位句It was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on

Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. 主要意思是直到寒武纪才能够监测生物多样性。言外之意就是

在寒武纪之前就不能监测生物多样性, 对应B 选项。

Paragraph 2

Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this was the era “when dinosaurs ruled Earth,” when a wide variety of reptile species occupying many ecological niches. However, no group or species can maintain its dominance indefinitely, and when, after over 200 million years, the age of dinosaurs came to a dramatic end about 65 million years ago, mammals began to flourish, evolving from relatively few types of small terrestrial animals into the myriad of diverse species, including bats and whales, that we know today. Paleontologists label this point in Earth?s history as the end of the Cretaceous period and the beginning of the Tertiary period, often abbreviated as the K-T boundary. This time was also marked by changes in many other types of organisms. Overall, about 38 percent of the families of marine animals were lost, with percentages much higher in some groups Ammonoid mollusks went from being very diverse and abundant to being extinct. An extremely abundant set of planktonic marine animals called foraminifera largely disappeared, although they rebounded later. Among plants, the K-T boundary saw a sharp but brief rise in the abundance of

primitive vascular plants such as ferns, club mosses, horsetails, and conifers and other gymnosperms. The number of flowering plants (angiosperms) was reduced at this

time, but they then began to increase dramatically.

3. 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.

A. The dominance of dinosaurs came to an end 65 million years ago, at which

time mammals began to flourish and diversify.

B. Because no group of species can remain dominant forever, mammals became

the dominant group when dinosaurs became extinct.

C. After being the dominant group for more than 200 million years, the age of dinosaurs came to a dramatic end 65 million years ago.

D. The diverse group of mammals that we know today, including bats and

whales, evolved from small terrestrial forms that had been dominated by

dinosaurs.

答案 B

解析句子简化题: 该长句其实是2 个长句的并列; 主要分成2 个意思: 第一是没有任何一种生物能永远地统治, 第二是恐龙灭亡之后, 哺乳动物开始发展

统治,且2 层意思之间可以构成因果关系。所以只有 B 选项满足所有条件。

4. According to paragraph 2, why are dinosaurs popularly said to have “ruled Earth”during the Cretaceous period?

A. Dinosaurs were the only species of reptile that existed during the whole of

the Cretaceous period.

B. Dinosaurs won the battle for food resources over mammals during the Cretaceous period.

C. Dinosaurs survived extinction during the Cretaceous period, whereas many

other animal species did not.

D. Dinosaurs were the physically and ecologically dominant animals during the Cretaceous period.

答案 D

解析细节题: 定位句Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this

was the era “when dinosaurs ruled Earth,” when a wide variety of reptile

species occupying many ecological niches. 对应D 选项。

5. According to paragraph 2, which of the following species initially increased in

number at the K-T boundary?

A. Dinosaurs

B. Foraminifera

C. Ferns

D. Ammonoid mollusks

答案 D

解析细节题: 定位句Paleontologists label this point in Earth?s history as the end of the Cretaceous period and the beginning of the Tertiary period, often

abbreviated as the K-T boundary. This time was also marked by changes in

many other types of organisms. Overall, about 38 percent of the families of

marine animals were lost, with percentages much higher in some groups

Ammonoid mollusks went from being very diverse and abundant to being

extinct. 题干中的范围限定initially, 因此只可能是Ammonoid mollusk, 选

D。

Paragraph 3

What caused these changes? For many years scientists assumed that a cooling of the climate was responsible, with dinosaurs being particularly vulnerable because, like modern reptiles, they were ectothermic (dependant on environmental heat, or

cold-blooded). It is now widely believed that at least some species of dinosaurs had a metabolic rate high enough for them to be endotherms (animals that maintain a relatively consistent body temperature by generating heat internally). Nevertheless, climatic explanations for the L-T extinction are not really challenged by the ideas that dinosaurs may have been endothermic, because even endotherms can be affected by a significant change in the climate.

6. Why does the author note that “even endotherms can be affected by a significant change in the climate”?

A. To argue that there was a significant climate at the time that endothermic dinosaurs became extinct

B. To argue that climate change caused some dinosaurs to evolve as endotherms

C. To support the view that at least some of the dinosaurs that became extinct

were endotherms

D. To defend climate change as possible explanation for the extinction of

dinosaurs

答案 D

解析修辞目的题: 题干中的even 甚至, 表示程度的递进。定位句Nevertheless, climatic explanations for the L-T extinction are not really challenged by the

ideas that dinosaurs may have been endothermic 。即后半句的原因解释了气候

理论为什么不被反驳。

Paragraph 4

Explanation for the K-T extinction were revolutionized in 1980 when a group of

physical scientists led by Luis Alvarez proposed that 65 million years ago Earth was struck by a 10-killometer-wide meteorite traveling at 90,000 kilometers per hour.

They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis

to very low levels. Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic

event caused the massive extinctions. Initially, the meteorite theory was based on a single line of evidence. At locations around the globe, geologists have found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. Irridium is an element that is usually uncommon near Earth?s surface, but it is abundant in some meteorites. Therefore, Alvarez and his colleagues concluded that it was likely that the iridium in sedimentary rocks deposited

at the K-T boundary had originated in a giant meteorite or asteroid. Most scientists

came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.

7. The word “generated” in the passage is closest in mea ning to

A. collected

B. produced

C. spread

D. added

答案 B

解析词汇题: generate 产生; 引起, 对应 B 选项, 产生。

8. The word “extensive” in the passage is closest in meaning to

A. widespread

B. sudden

C. numerous

D. subsequent

答案 A

解析词汇题: extensive, 广泛的, 对应A 选项, 广泛的。

9. According to paragraph 4, all of the following contributed to the massive extinctions of the K-T period EXCEPT:

A. tidal waves

B. fires

C. insufficient solar radiation

D. iridium

答案 D

解析否定细节题: 定位句Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions. 对应A 选项, B 选项。定位

句They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. 意思是这种冲击产生了大量的厚尘云, 遮

蔽了天空和阳光。对应C 选项。而D 选项, iridium 是有关灭绝的证据, 但

并非构成灭绝的原因。

10. According to paragraph 4, which of the following statements explains the importance of the discovery of high levels of iridium rocks?

A. It provided evidence that overexposure to solar radiation led to the K-T extinction.

B. It showed that more than one cataclysmic event was responsible for the K-T extinction.

C. It suggested that the cause of the K-T extinction may have been a meteorite striking Earth.

D. It provided evidence that the K-T extinction occurred 65 million years ago.

答案 C

解析细节题: 定位句Initially, the meteorite theory was based on a single line of evidence. At locations around the globe, geologists have found an unusually

high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. 意思是说小行星撞击理论一开始主要的证据就

是在地球的岩石中发现了大量的iridium (铱)。因此其重要性就是说明该撞

击理论是物种大灭绝的原因。

11. According to paragraph 4, which of the following is true about the Yucatan Peninsula?

A. The circular formation there was caused by a meteorite impact 65 million years ago.

B. Sedimentary rocks from that area have the lowest iridium concentration of any rocks on Earth.

C. There is evidence that a huge tidal wave occurred there 65 million years ago.

D. Evidence found there challenged the meteorite impact theory.

答案 A

解析细节题: 定位句Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago. 意思是说在Yucatan Peninsula 背岸的大坑

是陨石撞击的结果。对应A 选项

12. Which of the following can be inferred from paragraph 4 about the meteorite theory?

A. The data originally presented as evidence for the theory were eventually rejected.

B. Many scientists did not accept it when it was first proposed.

C. It has not been widely accepted as an explanation for the K-T extinction.

D. Alvarez subsequently revised it after a circular formation was found in the Yucatan Peninsula.

答案 B

解析推断题: 定位句Initially, the meteorite theory was based on a single line of evidence. 一开始仅依赖于单一证据的理论, 暗示了证据还不够充分。定位

句Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about

65 million years ago. 在环形坑证据出现之后大多数的科学家才开始接受小

行星撞击理论, 也就是说一开始大多数科学家对该理论是持有怀疑态度

的。

即答案就是B。

13. Look at the four squares [█] that indicate where the following sentence could be added to the passage

Paragraph 4:

Explanation for the K-T extinction were revolutionized in 1980 when a group of physical scientists led by Luis Alvarez proposed that 65 million years ago Earth was struck by a 10-killometer-wide meteorite traveling at 90,000 kilometers per hour. They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis

to very low levels. Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions.■Initially, the meteorite theory was based on a single line of evidence.■At locations around the globe, geologists have found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago.■Iridium is an element that is usually uncommon near Earth’s surface, but it is abundant in some meteorites.■Therefore, Alvarez and his colleagues concluded that it was likely that the iridium in sedimentary rocks deposited at the K-T boundary had originated in a giant meteorite or asteroid. Most scientists came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.

This focused on the chemical composition of ancient rocks.

Where would the sentence best fit?

答案第二个方框

解析句子插入题: 给出的句子中出现了this 的指代提示, 表示前面的内容可能与石头的化学组成无关, 而该句的下一句应该与化学组成有关。因此只有

第二个方框满足条件。在第二个方框之后才出现了对于iridium 的讨论。

14. 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.

The K-T extinction 65 million years ago is the best known of the five major

extinction episodes since the Cambrian period.

Answer Choices

A. Collectively, the five major extinction episodes resulted in the elimination of a larger number of species than did all the minor extinction events.

错。定位第一段The five major mass extinctions receive most of the attention, but they are only one end of a spectrum of extinction events. Collectively, more

species went extinct during smaller events that were less dramatic but more frequent. 原文说更多的物种在规模更小但是更频繁的事故中灭绝了, 因此

A 选项的中的比较信息则不成立。所以A 选项错误。

B. The K-T extinction eliminated the dinosaurs and ammonoid mollusks but was followed by the diversification of mammals and gymnospermous plants.

正确。对应第二段段落大意, 没有永生的统治者, 恐龙之后现在是哺乳动物和植物的天下。

C. An extreme cooling of the climate could not have caused the K-T extinction of dinosaurs, because, while most dinosaurs depended on environmental heat, some

did not.

错。定位第三段, 其主旨是气候变冷可能导致恐龙灭绝。而C 选项的观点与该主旨背道而驰, 所以错误。

D. The K-T extinction of the dinosaurs is the only mass extinction that has been explained by the impact of a meteorite.

错。原文并没有提到其他的大灭绝又没有合理的解释, 所以D 选项错误。

E. In 1980 Luis Alvarez proposed that the K-T extinction was caused by ecological disasters brought about by the impact of a meteorite striking Earth.

正确。对应第四段主旨: 小行星撞击地球假说。

F . A high concentration of iridium in sedimentary rocks at the K-T boundary and a large impact crater in the Yucatan Peninsula from 65 million years ago strongly support Alvarez? hypothesis.

正确。对应第四段解释小行星撞击地球假说的重要证据。一个证据是Iridium 在地球岩石中的大量出现, 另一个证据是巨大环形坑的发现。

摘要题

答案BEF