GMAT考试-GWD-CR解析-weaken/explain/assumption

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GWD-2-Q19:
Sunflowers growing in pots were placed, with their roots submerged, in the pond contaminated with radioactive elements.  The sunflowers kept growing; in the process, they absorbed radioactive elements.  Within twelve days, 85 percent of the radioactive elements were removed from the water, which is no less than can be accomplished with the much more expensive conventional filtration techniques.  Scientists therefore propose using sunflowers for decontamination wherever there are radioactively contaminated ponds.

Which of the following, if true, points to a limitation on the applicability of the proposed method of decontamination? 措施的有效性，无法达到目的

A.        Some plants other than sunflowers can also remove radioactive elements from water.
B.        The water in many ponds contaminated with radioactive elements is so cold that it would kill sunflowers whose roots were submerged in it.
C.        Sunflowers that grow with their roots submerged in water grow less well than sunflowers growing under optimal conditions on dry land.
D.        Only species of sunflowers with large leaves can have their roots submerged in water and still keep growing.
E.        In ponds in which the circulation of the water is artificially increased, sunflowers absorb radioactive elements far faster than they do in other ponds.

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GWD-6-Q40**:
It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite.  However, strains of bacteria from different planets would probably have substantial differences in protein structure that would persist over time, and no two bacterial strains on Earth are different enough to have arisen on different planets.  So, even if bacteria did arrive on Earth from Mars, they must have died out.

The argument is most vulnerable to which of the following criticisms?

A.        It fails to establish whether bacteria actually developed on Mars.
B.        It fails to establish how likely it is that Martian bacteria were transported to Earth.
C.        It fails to consider whether there were means other than meteorites by which Martian bacteria could have been carried to Earth.（结论说的是来自火星的细菌就算到了地球也已经灭绝了，而不是通过陨石没法来到地球）
D.        It fails to consider whether all bacteria now on Earth could have arisen from transported Martian bacteria.
E.        It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out. Focus应该是来自火星的Bacteria。

如果地球上所有的细菌全部来自火星，当然不可能有两种不同的结构，IF这个成立，那么文章的结论说来自火星的灭绝了就错了！因为现有的细菌来自火星，但却没有灭！
我觉得E无关：It fails to consider whether there could have been strains of bacteria that originated on Earth and later died out.
前提：地球上的B都一样，不可能来自火星；结论：即使有B来到地球，也都死光光了（不能影响地球的B）—>削：地球上的B可能是从火星B发展而来（把GAP拎出来）
而E说的是“没有考虑到可能有起源于地球的B而后来灭绝了”，也就是说E认为以前在地球上曾经存在过B，后来死了。这个与火星的B到地球，进而影响地球的B是无关的

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GWD-8-Q38:
Unless tiger hunting decreases, tigers will soon be extinct in the wild. The countries in which the tigers’ habitats are located are currently debating joint legislation that would ban tiger hunting. Thus, if these countries can successfully enforce this legislation, the survival of tigers in the wild will be ensured.

The reasoning in the argument is most vulnerable to criticism on the grounds that the argument

A. assumes without sufficient warrant that a ban on tiger hunting could be successfully enforced反前提
B. considers the effects of hunting on tigers without also considering the effects of hunting on other endangered animal species
C. fails to take into account how often tiger hunters are unsuccessful in their attempts to kill tigers
D. neglects to consider the results of governmental attempts in the past to limit tiger hunting
E. takes the removal of an impediment to the tigers’ survival as a guarantee of their survival[E] 条件性结论
原文推理：因为NOT EXTINCT----->HUNTING DECREASE。所以HUNTING DECREAS（BAN HUNTING成功）------>NOT EXTINCT。很容易看出逻辑错误为逆命题的错误，即将必要条件（HUNTING DECREASE）当作充分条件。即E。

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T-4-Q38
In one state, all cities and most towns have antismoking ordinances, a petition entitled “Petition for Statewide Smoking Restriction” is being circulated to voters by campaign workers who ask only, “Do you want to sign a petition for statewide smoking restriction?” The petition advocates a state law banning smoking in most retail establishments and in government offices that are open to the public.

Which of the following circumstances would make the petition as circulated misleading to voters who understand the proposal as extending the local ordinances statewide?
A.        Health costs associated with smoking cause health insurance premiums to rise for everyone and so affect nonsmokers.
B.        In rural areas of the state, there are relatively few retail establishments and government offices that are open to the public. (地域方面的关键词，因为该戒烟调查是想在大多数零售商场和办公室等公共场合起作用，而不是有些选民误以为的在全州进行全面禁烟)
C.        The state law would supersede the local antismoking ordinances, which contain stronger bans than the state law does.（不是州法要替代当地法）
D.        There is considerable sentiment among voters in most areas of the state for restriction of smoking.
E.        The state law would not affect existing local ordinances banning smoking in places where the fire authorities have determined that smoking would constitute a fire hazard.

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T-4-Q20 天山-7-22
The violent crime rate (number of violent crimes per 1,000 residents) in Meadowbrook is 60 percent higher now than it was four years ago. The corresponding increase for Parkdale is only 10 percent. These figures support the conclusion that residents of Meadowbrook are more likely to become victims of violent crime than are residents of Parkdale.
The argument above is flawed because it fails to take into account

A.        Changes in the population density of both Meadowbrook and Parkdale over the past four years.
B.        How the rate of population growth in Meadowbrook over the past four years compares to the corresponding rate for Parkdale
C.        The ratio of violent to nonviolent crimes committed during the past four years in Meadowbrook and Parkdale
D.        The violent crime rates in Meadowbrook and Parkdale four years ago（应该是M&P横向比较，而不是拿两者纵向比较的结果再比较）
E.        How Meadowbrooks’ expenditures for crime prevention over the past four years compare to Parkdale’s expenditures.
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