GMAT-OG12逻辑题推理过程-WEAKEN：削弱

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1.
“Life expectancy” is the average age at death of the entire live-born population. In the middle of the nineteenth century, life expectancy in North America was 40 years, whereas now it is nearly 80 years. Thus, in those days, people must have been considered old at an age that we now consider the prime of life.

Which of the following, if true, undermines the argument above?

(A) In the middle of the nineteenth century, the population of North America was significantly smaller than it is today. （不相关：多个因素之一）
(B) Most of the gains in life expectancy in the last 150 years have come from reductions in the number of infants who die in their first year of life. （相关度大：确定）
(C) Many of the people who live to an advanced age today do so only because of medical technology that was unknown in the nineteenth century. （不相关：支持）
(D) The proportion of people who die in their seventies is significantly smaller today than is the proportion of people who die in their eighties. （不相关：支持）
(E) More people in the middle of the nineteenth century engaged regularly in vigorous physical activity than do so today. （相关度小：不确定）

分类：WEAKEN
看原文：
前提1（隐含假设）：通常寿命集中于平均寿命附近
前提2（事实）：平均寿命不同
总结论（推测）：相同年龄的衰老程度不同
找答案：指出前提的具体性，从而否定一般性
TEST：否定前提，进而否定结论
模型或要素：平均寿命 = 年龄总和 / 总人口
考点：一般情况不一般；比较，找差异

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5.
A company is considering changing its policy concerning daily working hours. Currently, this company requires all employees to arrive at work at 8 a.m. The proposed policy would permit each employee to decide when to arrive—from as early as 6 a.m. to as late as 11 a.m.

The adoption of this policy would be most likely to decrease employees’ productivity if the employees’ job functions required them to

(A) work without interruption from other employees（不相关：不需要合作，相反）
(B) consult at least once a day with employees from other companies（不相关：不需要经常合作，相反）
(C) submit their work for a supervisor’s eventual approval（不相关：不需要经常合作，相反）
(D) interact frequently with each other throughout the entire workday（相关：经常合作，支持）
(E) undertake projects that take several days to complete（不相关：没提到合作）

分类：ASSUMPTION
看原文：
前提1（隐含假设）：弹性工作制不利于合作
前提2（事实）：工作需要经常合作
总结论（推测）：弹性工作制降低生产率
找答案：SUPPORT结论
TEST：取非，否定
模型或要素：时间、频率
考点：补充不利因素；方案，加限制

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10.
Cable-television spokesperson: Subscriptions to cable television are a bargain in comparison to “free” television. Remember that “free” television is not really free. It is consumers, in the end, who pay for the costly advertising that supports “free” television.

Which of the following, if true, is most damaging to the position of the cable-television spokesperson?

(A) Consumers who do not own television sets are less likely to be influenced in their purchasing decisions by television advertising than are consumers who own television sets. （不相关：不看电视者）
(B) Subscriptions to cable television include access to some public-television channels, which do not accept advertising. （不相关：公共电视，支持）
(C) For locations with poor television reception, cable television provides picture quality superior to that provided by free television. （不相关：接收质量）
(D) There is as much advertising on many cable-television channels as there is on “free” television channels. （相关：有线不免费）
(E) Cable-television subscribers can choose which channels they wish to receive. （不相关：接收频道）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：电视、费用、广告
考点：否定比较优势；比较，找差异

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15.
A conservation group in the United States is trying to change the long-standing image of bats as frightening creatures. The group contends that bats are feared and persecuted solely because they are shy animals that are active only at night.

Which of the following, if true, would cast the most serious doubt on the accuracy of the group’s contention?

(A) Bats are steadily losing natural roosting places such as caves and hollow trees and are thus turning to more developed areas for roosting. （不相关：短期变化）
(B) Bats are the chief consumers of nocturnal insects and thus can help make their hunting territory more pleasant for humans. （不相关：益处）
(C) Bats are regarded as frightening creatures not only in the United States but also in Europe, Africa, and South America. （不相关：范围）
(D) Raccoons and owls are shy and active only at night, yet they are not generally feared and persecuted. （相关：习性相同，形象不同）
(E) People know more about the behavior of other greatly feared animal species, such as lions, alligators, and snakes, than they do about the behavior of bats. （不相关：了解程度，支持）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：长期形象、习性
考点：找出反例；解释，找例外

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23.
A drug that is highly effective in treating many types of infection can, at present, be obtained only from the bark of the ibora, a tree that is quite rare in the wild. It takes the bark of 5,000 trees to make one kilogram of the drug. It follows, therefore, that continued production of the drug must inevitably lead to the ibora’s extinction.

Which of the following, if true, most seriously weakens the argument above?

(A) The drug made from ibora bark is dispensed to doctors from a central authority. （不相关：药物分配）
(B) The drug made from ibora bark is expensive to produce. （不相关：制造成本）
(C) The leaves of the ibora are used in a number of medical products. （相关度小：其他灭绝原因）
(D) The ibora can be propagated from cuttings and grown under cultivation. （相关：人工种植）
(E) The ibora generally grows in largely inaccessible places. （不相关：收获难度）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：药材、稀有、灭绝、自然生长、人工种植
考点：提供解决方案；问题，找方案

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30.
Robot satellites relay important communications and identify weather patterns. Because the satellites can be repaired only in orbit, astronauts are needed to repair them. Without repairs, the satellites would eventually malfunction. Therefore, space flights carrying astronauts must continue.

Which of the following, if true, would most seriously weaken the argument above?

(A) Satellites falling from orbit because of malfunctions burn up in the atmosphere. （不相关：故障后果，支持）
(B) Although satellites are indispensable in the identification of weather patterns, weather forecasters also make some use of computer projections to identify weather patterns. （不相关：卫星作用，支持）
(C) The government, responding to public pressure, has decided to cut the budget for space flights and put more money into social welfare programs. （不相关：其他原因，与推理无关）
(D) Repair of satellites requires heavy equipment, which adds to the amount of fuel needed to lift a spaceship carrying astronauts into orbit. （不相关：燃料、设备）
(E) Technical obsolescence of robot satellites makes repairing them more costly and less practical than sending new, improved satellites into orbit. （相关：新卫星，否定前提）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：卫星、维修、宇航员
考点：提供解决方案；问题，找方案

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35.
Last year the rate of inflation was 1.2 percent, but for the current year it has been 4 percent. We can conclude that inflation is on an upward trend and the rate will be still higher next year.

Which of the following, if true, most seriously weakens the conclusion above?

(A) The inflation figures were computed on the basis of a representative sample of economic data rather than all of the available data. （不相关：样本代表性）
(B) Last year a dip in oil prices brought inflation temporarily below its recent stable annual level of 4 percent. （相关：有其他原因）
(C) Increases in the pay of some workers are tied to the level of inflation, and at an inflation rate of 4 percent or above, these pay raises constitute a force causing further inflation. （不相关：上涨因素，支持）
(D) The 1.2 percent rate of inflation last year represented a 10-year low. （不相关：时间范围，信息不足）
(E) Government intervention cannot affect the rate of inflation to any significant degree. （不相关：政府干预）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：通胀率、趋势
考点：找出其他原因；变化，找原因

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36.
Offshore oil-drilling operations entail an unavoidable risk of an oil spill, but importing oil on tankers presently entails an even greater such risk per barrel of oil. Therefore, if we are to reduce the risk of an oil spill without curtailing our use of oil, we must invest more in offshore operations and import less oil on tankers.

Which of the following, if true, most seriously weakens the argument above?

(A) Tankers can easily be redesigned so that their use entails less risk of an oil spill. （相关：改进油轮，否定前提）
(B) Oil spills caused by tankers have generally been more serious than those caused by offshore operations. （不相关：油轮弊端，支持）
(C) The impact of offshore operations on the environment can be controlled by careful management. （不相关：离岸改进，支持）
(D) Offshore operations usually damage the ocean floor, but tankers rarely cause such damage. （不相关：离岸其他弊端）
(E) Importing oil on tankers is currently less expensive than drilling for it offshore. （不相关：油轮成本优势）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：石油泄露、离岸、油轮、进口
考点：否定比较优势；比较，找差异

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40.
In the last decade there has been a significant decrease in coffee consumption. During this same time, there has been increasing publicity about the adverse long-term effects on health of the caffeine in coffee. Therefore, the decrease in coffee consumption must have been caused by consumers’ awareness of the harmful effects of caffeine.

Which of the following, if true, most seriously calls into question the explanation above?

(A) On average, people consume 30 percent less coffee today than they did 10 years ago. （不相关：现象重述）
(B) Heavy coffee drinkers may have mild withdrawal symptoms, such as headaches, for a day or so after significantly decreasing their coffee consumption. （不相关：咖啡饮用减少效果，非原因）
(C) Sales of specialty types of coffee have held steady as sales of regular brands have declined. （不相关：部分咖啡消费下降，支持）
(D) The consumption of fruit juices and caffeine-free herbal teas has increased over the past decade. （不相关：其他消费上升，支持）
(E) Coffee prices increased steadily in the past decade because of unusually severe frosts in coffee-growing nations. （相关：有其他因素）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：咖啡、消费下滑、健康意识
考点：找出其他原因；解释，找差异

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45.
Some anthropologists study modern-day societies of foragers in an effort to learn about our ancient ancestors who were also foragers. A flaw in this strategy is that forager societies are extremely varied. Indeed, any forager society with which anthropologists are familiar has had considerable contact with modern, non-forager societies.

Which of the following, if true, would most weaken the criticism made above of the anthropologists’ strategy?

(A) All forager societies throughout history have had a number of important features in common that are absent from other types of societies. （相关：延续历史、现代不同）
(B) Most ancient forager societies either dissolved or made a transition to another way of life. （不相关：社会转变）
(C) All anthropologists study one kind or another of modern-day society. （不相关：学者行为）
(D) Many anthropologists who study modern-day forager societies do not draw inferences about ancient societies on the basis of their studies. （不相关：研究现代社会的缺点）
(E) Even those modern-day forager societies that have not had significant contact with modern societies are importantly different from ancient forager societies. （不相关：现代与历史不同，支持）

分类：
看原文：
前提1（隐含假设）：
前提2（事实）：
总结论（推测）：
找答案：
TEST：
模型或要素：社会沿袭、联系、区别
考点：找出其他原因；驳斥，找证据