GMAT考试-GWD-CR解析-WEAKEN

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三种方式weaken：
1。举反例证明结论错，如：缺少必要assumption/缺少不变量：如平均值、总量、百分比、比率等；
2。找出更合理他因；
3。削弱“证据”与结论间的因果关联性
4。取非支持为最削弱项
GWD-1-Q13:选了C
In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years.  Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.

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

A.        Florida attracts more people who move from one state to another when they retire than does any other state.
B.        The number of people who move out of Florida to accept employment in other states has increased over the past ten years.
C.        There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees. 无关比较，还是说明会有不良的经济影响。
D.        The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years. Total*%=the number of people who retired to F，应该以在F养老的人总数为衡量标准，因为百分比会因分母变大而变小，不具纵向参考性，横向比较才有参考性）
E.        The number of people who left Florida when they retired to live in another state was greater last year than it was ten years ago.[D] 百分比和绝对数的换算

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T-4-Q21粗心
The OLEX Petroleum Company has recently determined that it could cut its refining costs by closing its Grenville refinery and consolidating all refining at its Tasberg refinery. Closing the Grenville refinery, however, would mean the immediate loss of about 1,2000 jobs in the Grenville area. Eventually the lives of more than 10,000 people would be seriously disrupted. Therefore, OLEX’s decision, announced yesterday, to keep Grenville open shows that at OLEX social concerns sometimes outweigh the desire for higher profits.
又是成本收益
要证明OLEX决定不关G是出于利润的考虑而不是社会责任
Which of the following, if true, most seriously undermines the argument given?
A.        The Grenville refinery, although it operates at a higher cost than the Tasberg refinery, has nevertheless been moderately profitable for many years.这里如果是significant就对了
B.        Even though OLEX could consolidate all its refining at the Tasberg plant, doing so at the Grenville plant would not be feasible.
C.        The Tasberg refinery is more favorably situated than the Grenville refinery with respect to the major supply routes for raw petroleum.
D.        If the Grenville refinery were ever closed and operations at the Tasberg refinery expanded, job openings at Tasberg would to the extent possible be filled with people formerly employed at Grenville.
E.        Closure of the Grenville refinery would mean compliance, at enormous cost, with demanding local codes regulating the cleanup of abandoned industrial sites.关闭后成本反而大

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GWD29-Q9:
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats.  To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds.  Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows.  Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A.        The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported collisions between manatees and boats.
B.        Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat traffic.
C.        Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the endangered manatee population.
D.        The sound of a boat engine generally travels much further under water than it does through the air.
E.        When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal background noise.

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15.
Healthy lungs produce a natural antibiotic that protects them from infection by routinely killing harmful bacteria on airway surfaces. People with cystic fibroses, however, are unable to fight off such bacteria, even though their lungs produce normal amounts of the antibiotic. Since the fluid on airway surfaces in the lungs of people with cystic fibrosis bas an abnormally high salt concentration, scientists hypothesize that in high salt environments the antibiotic becomes ineffective at killing harmful bacteria.
高盐密度导致抗生体不能消灭有害细菌
削弱方法：举反例：没有高盐密度抗生体也不能消灭有害细菌
          抗生体不能消灭有害细菌导致高盐密度
          。。。
Which of the following, if it were obtained as an experimental result, would most decisively undermine the scientists’ hypothesis?
A.        Healthy lungs in which the salt concentration of the airway-surface fluid has been substantially increased are able to reestablish their normal salt concentration within a relatively short period of time.
B.        The antibiotic produced by the lungs is effective at killing harmful bacteria even when salt concentrations are below levels typical of healthy lungs.
C.        The salt concentration of the airway-surface fluid in the lungs of people who suffer from cystic fibrosis tends to return to its former high levels after having been reduced to levels typical of healthy lungs.
D.        The lungs of people who suffer from cystic fibrosis are unable to fight off harmful bacteria even when the salt concentration is reduced to levels typical of healthy lungs.
E.        The salt concentration in the airway-surface fluid of people whose lungs produce lower-than-average amounts of the antibiotic is generally much lower than that typical of healthy lungs.

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14
In 1983 Argonia’s currency, the argon, underwent a reduction in value relative to the world’s strongest currencies. This reduction resulted in a significant increase in Argonia’s exports over 1982 levels. In 1987 a similar reduction in the value of the argon led to another increase in Argonia’s exports. Faced with the need to increase exports yet again, Argonia’s finance minister has proposed another reduction in the value of the argon.
本币贬值----出口增加。
重复操作
Which of the following, if true, most strongly supports the prediction that the finance minister’s plan will not result in a significant increase in Argonia’s exports next year?
A.        The value of the argon rose sharply last year against the world’s strongest currencies.
B.        In 1988 the argon lost a small amount of its value, and Aronian exports rose slightly in 1989.
C.        The value of Argonia’s exports was lower last year than it was the year before.
D.        All of Argonia’s export products are made by factories that were operating at full capacity last year, and new factories would take years to build.方案不可行。就算想增加也没有能力增加了
E.        Reductions in the value of the argon have almost always led to significant reductions in the amount of goods and services that Argonians purchase from abroad.

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GWD-13-Q5*:
Vorland’s government is planning a nationwide ban on smoking in restaurants.  The objection that the ban would reduce restaurants’ revenues is ill founded.  Several towns in Vorland enacted restaurant smoking restrictions five years ago.  Since then, the amount the government collects in restaurant meal taxes in those towns has increased 34 percent, on average, but only 26 percent elsewhere in Vorland.  The amount collected in restaurant meal taxes closely reflects restaurants’ revenues.

Which of the following, if true, most undermines the defense of the government’s plan?

A.        When the state first imposed a restaurant meal tax, opponents predicted that restaurants’ revenues would decline as a result, a prediction that proved to be correct in the short term.
B.        The tax on meals in restaurants is higher than the tax on many other goods and services.
C.        Over the last five years, smoking has steadily declined throughout Vorland.
D.        In many of the towns that restrict smoking in restaurants, restaurants can maintain separate dining areas where smoking is permitted.这里weaken的不是结果，而是证据与结果间的因果关联性
E.        Over the last five years, government revenues from sales taxes have grown no faster in the towns with restaurant smoking restrictions than in the towns that have no such restrictions.
原文推理：禁止在饭店吸烟——》预期饭店收入会减少——》事实上饭店餐税增加（收入增加）——》禁止在饭店吸烟不会降低饭店收入
D说：在大多数的地方的饭店可以维持吸烟，因此饭店收入增加和禁止吸烟不能形成有效的因果关系（削弱）
同意D。
1。结论：禁烟对。证据：自从五年前部分镇禁烟后，restaurants收入增长大于没禁烟的镇（meal taxes 增长，而meal taxes 又closely反映收入的增长）。它隐含的意思是禁烟使收入增长，从而说明禁烟是对的。D说在禁烟的小镇，restaurants仍保留吸烟区，允许吸烟。说明不是禁烟使restaurants的收入增加。WEAKEN原文证据对结论的证明力。
2。E不但错在前面所说的sales taxes 和原文无关（原文是meal taxes ，而且已说meal taxes 准确的反映收入 ），而且原文说的是对restaurants的收入的影响，E说的是镇的税收的变化，原文没有任何信息使人想到这个镇的税收的变化是restaurants导致的还是别的行业导致的。故E不能WEAKEN原文的结论。

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GWD-12-Q16:
Certain genetically modified strains品种 of maize玉米 produce a natural insecticide that protects against maize-eating insects.  The insecticide occurs throughout the plant, including its pollen.  Maize pollen is dispersed by the wind and often blows onto milkweed plants that grow near maize fields.  Caterpillars of monarch butterflies feed exclusively on milkweed leaves.  When, in experiments, these caterpillars were fed milkweed leaves dusted with pollen from modified maize plants, they died.  Therefore, use of the modified maize inadvertently imperils monarch butterflies.

Which of the following, if true, most seriously weakens the argument?
吃milkweed上玉米花粉导致蝴蝶幼虫死亡。
A.        Per unit of volume, the natural insecticide produced by the genetically modified maize plants is less toxic to insects than are many commercial insecticides commonly used on maize plants.
B.        Standard weed-control practices that have been used by farmers for decades have largely eliminated milkweed plants from certain areas where monarch-butterfly caterpillars were once common.
C.        The experiments showed that the caterpillars were not harmed by contact with the pollen from the genetically modified plants unless they ingested it.
D.        The maize-eating insects that the natural insecticide protects against do not feed on the pollen of the maize plant.结论的特殊性这里讨论蝴蝶。
E.        Airborne maize pollen tends to collect on the middle leaves of milkweed plants and monarch caterpillars feed only on the plant’s tender upper leaves.

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GWD-12-Q15:
FastMart, a convenience store chain, is planning to add pancake syrup to the items it sells.  FastMart stores do not have shelf space to stock more than one variety of syrup.  Surveys of FastMart customers indicate that one-fourth of them prefer low-calorie syrup, while three-fourths prefer regular syrup.  Since FastMart’s highest priority is to maximize sales, the obvious strategy for it is to stock regular syrup.
找stock regular syrup不能maximize sales的
Which of the following, if true, most seriously weakens the argument?

A:        People buying pancake syrup at convenience stores, unlike those buying it at supermarkets, generally buy it only a few times.
B.        People who prefer low-calorie syrup generally use about the same amount of syrup on their pancakes as those who prefer regular syrup.
C.        Regular syrup does not sell for a higher price per unit than low-calorie syrup.
D.        In general, customers who prefer regular syrup will buy low-calorie syrup if regular is unavailable, but those who prefer low-calorie will not buy regular syrup. (在没有自己要的syrup时，喜欢regular的会退而求其次，喜欢low-c的就不买了)
E.        Sales of syrup are not expected to account for a large proportion of total dollar sales at the average FastMart store.
regular syrup=3/4 customer
low calorie syrup= 100% customer

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GWD-12-Q2:简单
Scientists are discussing ways to remove excess carbon dioxide from the atmosphere by increasing the amount that is absorbed by plant life.  One plan to accomplish this is to establish giant floating seaweed farms in the oceans.  When the seaweed plants die, they will be disposed of by being burned for fuel.

Which of the following, if true, would indicate the most serious weakness in the plan above?

A.        Some areas of ocean in the Southern Hemisphere do not contain sufficient nutrients to support large seaweed farms.
B.        When a seaweed plant is burned, it releases an amount of carbon dioxide comparable to the amount it has absorbed in its lifetime.
C.        Even if seaweed farms prove effective, some people will be reluctant to switch to this new fuel.
D.        Each year about seven billion tons of carbon dioxide are released into the atmosphere but only about five billion tons are absorbed by plant life.
E.        Seaweed farms would make more money by farming seaweed to sell as nutritional supplements than by farming seaweed to sell as fuel.

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GWD-11-Q41:
Charcoal from a hearth site in Colorado, 2,000 miles south of Alaska, is known to be 11,200 years old.  Researchers reasoned that, since glaciers prevented human migration south from the Alaska-Siberia land bridge between 18,000 and 11,000 years ago, humans must have come to the Americas more than 18,000 years ago.

Which of the following pieces of new evidence would cast doubt on the conclusion drawn above?

A.        Using new radiocarbon dating techniques, it was determined that the charcoal from the Colorado site was at least 11,400 years old.
B.        Another campsite was found in New Mexico with remains dated at 16,000 years old.
C.        A computer simulation of glacial activity showed that it would already have been impossible for humans to travel south overland from Alaska 18,500 years ago.
D.        Using new radiocarbon dating techniques, it was proved that an ice-free corridor allowed passage south from the Alaska-Siberia land bridge at least 11,400 years ago.
E.        Studies of various other hunting-gathering populations showed convincingly that, once the glaciers allowed passage, humans could have migrated from Alaska to Colorado in about 20 years.
这是WEAKEN题。原文的推理是：木炭是11200年前的（即11200年前由人类活动），而在11000和18000年前之间，冰川在人阻止人类迁到北美。所以人类是在18000年前到达的。其前提是在11000和18000之间，人类无法通过其它途径到达北美。D提出了另外的途径。所以WEAKNE结论。
B错在时间不是campsite的时间，而是REMAINS的时间，这个remains的时间并不代表有人类活动的时间。比如这个remains是什麽更早的古物，是人类从别的地方带来的。所以它的时间不代表人类在北美活动的时间。B错也并不是因为New Mexico无关。B想混淆大家的是：在11000和18000这段时间里，new mexico 也有人住。（因为new mexico 在 colorado的南面，ETS想误导大家16000年时有人通过Alaska-Siberia land bridge）但B并不能weaken原推论。因为即使new mexico 16000有人住，这些人也可能是在18000之前就通过Alaska-Siberia land bridge 搬过来的。
E 人类迁移时间和原文无关。原文只是说11000到18000期间通道都被冰川冰冻，并没说期间有多久解冻，人类可通过