问一道一直都想不通的prep CR问题，请大家帮忙！

Hamburger530 · 发表于 2012-5-17 00:26:28

Although fullerenes--spherical molecules made entirely of carbon--were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite.Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.

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

(A) Confirming that the shungite genuinely contained fullerenes took careful experimentation.

(B) Some fullerenes have also been found on the remains of a small meteorite 陨星 that collided with a spacecraft.

(C) The mineral shungite itself contains large amounts of carbon, from which the fullerenes apparently formed.

(D) The naturally occurring fullerenes are arranged in a previously unknown crystalline structure.

(E) Shungite itself is formed only under distinctive conditions.

答案是D。可是我为什么觉得D无关呢。文中已经说了，they have since been found in nature, formed in fissures of the rare mineral shungite，已经是个既定的事实了。那么题目D中crystalline structure跟hypotheses about the state of the Earth's crust 又有什么关系呢？

谢谢！

Hamburger530 · 发表于 2012-5-17 00:44:04

Astronomer: Observations of the Shoemaker-Levi comet on its collision course with Jupiter showed that the comet broke into fragments before entering Jupiter's atmosphere in 1994, but they did not show how big those fragments were. In hopes of gaining some indication of the fragments' size, astronomers studied spectrographic analyses of Jupiter's outer atmosphere. These analyses revealed unprecedented traces of sulfur after the fragments' entry. The fragments themselves almost certainly contained no sulfur, but many astronomers believe that the cloud layer below Jupiter's outer atmosphere does contain sulfur. Since sulfur would have seeped into the outer atmosphere if comet fragments had penetrated this cloud layer, it is likely that some of the fragments were at least large enough to have passed through Jupiter's outer atmosphere without being burned up.

In the astronomer's argument, the two portions in boldface play which of the following roles?

(A) The first presents a circumstance for which the astronomer offers an explanation; the second is part of that explanation.
(B) The first acknowledges a consideration that weighs against the conclusion of the argument; the second is that conclusion.
(C) The first acknowledges a consideration that weighs against the conclusion of the argument; the second provides evidence in support of that conclusion.
(D) The first provides evidence in support of the conclusion of the argument; the second acknowledges a consideration that weighs against that conclusion.
(E) The first is a judgment advanced in support of the conclusion of the argument; the second is that conclusion.

我再加一道题。答案是E，我觉得也有理。不过A为什么不对，第二段BF不可以既做explanation又做conclusion吗？还是A错在前半句上？circumstance一般在BF上指什么呢？

谢谢！

Hamburger530 · 发表于 2012-5-17 00:53:01

Most of the world's supply of uranium currently comes from mines. It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market. Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

(A) Whether the uranium in deposits on land is rapidly being depleted （耗尽）根据题目的结论，因为找不到减少成本的方法，extract uranium from seawater不可能可行。题目用land uranium的即将耗尽来打击题目的结论。
(B) Whether most uranium is used near where it is mined
(C) Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater
(D) Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land
(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater

C （A）

已经开新帖了，我就索性多问提到。答案选A我选C，我知道A为什么对，但是C为什么不对，如果有了新的方法，不久是这个提议在商业上可行了吗？

谢谢！

Hamburger530 · 发表于 2012-5-17 00:58:32

Urban air contains more sulfur dioxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to sulfur dioxide, classes in an urban and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate sulfur dioxide.

lants in the urban greenhouse grew more slowly than those in the rural greenhouse.

Which of the following, if true, would it be most important to take into account in evaluating the result?

(A) The urban school was located in a part of the city in which levels of sulfur dioxide in the air were usually far lower than is typical for urban areas.
(B) At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
(C) The urban class conducting the experiment was larger than the rural class conducting the experiment.
(D) Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside. 其实这道题很简单，题目就是要问为什么生长环境相同，而urban的plant还是长得慢呢？
(E) Because of the higher levels of sulfur dioxide in the air at the urban school, the air filters for the urban school's greenhouse were changed more frequently than were those at the rural school.

我保证是最后一道了。这个题选D。可是D貌似跟二氧化碳的污染没有什么直接关系。能解释吗？

谢谢！

sdcar2010 · 发表于 2012-5-17 09:35:04

For the first Q, D is the answer.

1) Scientist synthesized a chemical called fullerenes.
2) Naturally occurring fullerenes were found in the mineral shungite.
3) Assumptions: a) The synthesized fullerenes and the naturally ocurring fullerenes in shungite have the same structure. b) If the same structure are found in two compounds, then the two compounds require the same conditions to form.
4) Conclusion: The condition on earth when the mineral shungite was formed could be known.

Answer D says the structure for fullerene in synthetic form are different from that in natural form of shungite. Hence, the assumption a) is wrong. So is the conclusion then.

Hamburger530 · 发表于 2012-5-17 21:13:59

D选项我懂了，谢谢。
再请问一下，C为什么不对呢，因为mineral shungite本身有碳的成分，而fullerenes是由碳的成分形成，有可能地质学家无法区分呢？

Hamburger530 · 发表于 2012-5-17 21:15:08

27. (31231-!-item-!-188;#058&004411)

Plant scientists have used genetic engineering on seeds to produce crop plants that are highly resistant to insect damage. Unfortunately, the seeds themselves are quite expensive, and the plants require more fertilizer and water to grow well than normal ones. Thus, for most farmers the savings on pesticides would not compensate for the higher seed costs and the cost of additional fertilizer. However, since consumer demand for grains, fruits, and vegetables grown without the use of pesticides continues to rise, the use of genetically engineered seeds of this kind is likely to become widespread.

In the argument given, the two portions in boldface play which of the following roles?

(A) The first supplies a context for the argument; the second is the argument's main conclusion.
(B) The first introduces a development that the argument predicts will have a certain outcome; the second is a state of affairs that the argument denies will be part of that outcome.
(C) The first presents a development that the argument predicts will have a certain outcome; the second acknowledges a consideration that weighs against that prediction.
(D) The first provides evidence to support a prediction that the argument seeks to defend; the second is that prediction.
(E) The first and the second each provide evidence to support the argument's main conclusion.

(C)

答案是C。那么A，B为什么不对呢？

mongmong · 发表于 2012-5-19 13:41:02

For the first Q, D is the answer.

1) Scientist synthesized a chemical called fullerenes.
2) Naturally occurring fullerenes were found in the mineral shungite.
3) Assumptions: a) The synthesized fullerenes and the naturally ocurring fullerenes in shungite have the same structure. b) If the same structure are found in two compounds, then the two compounds require the same conditions to form.
4) Conclusion: The condition on earth when the mineral shungite was formed could be known.

Answer D says the structure for fullerene in synthetic form are different from that in natural form of shungite. Hence, the assumption a) is wrong. So is the conclusion then.

-- by 会员 sdcar2010 (2012/5/17 9:35:04)

NN, 题干中第一句话写道"Although fullerenes - spherical molecules made entirely of carbon -- were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite." 这里的they指代前面的fullerenes, 也就是spherical molecules，两个不是同一样东西吗？

sdcar2010 · 发表于 2012-5-19 20:38:24

For the first Q, D is the answer.

1) Scientist synthesized a chemical called fullerenes.
2) Naturally occurring fullerenes were found in the mineral shungite.
3) Assumptions: a) The synthesized fullerenes and the naturally ocurring fullerenes in shungite have the same structure. b) If the same structure are found in two compounds, then the two compounds require the same conditions to form.
4) Conclusion: The condition on earth when the mineral shungite was formed could be known.

Answer D says the structure for fullerene in synthetic form are different from that in natural form of shungite. Hence, the assumption a) is wrong. So is the conclusion then.

-- by 会员 sdcar2010 (2012/5/17 9:35:04)

NN, 题干中第一句话写道"Although fullerenes - spherical molecules made entirely of carbon -- were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite." 这里的they指代前面的fullerenes, 也就是spherical molecules，两个不是同一样东西吗？

-- by 会员 mongmong (2012/5/19 13:41:02)

Yeah, they refer to both fullerenes and the spherical molecules. But there might be more than one condition to form these spherical molecules.

mongmong · 发表于 2012-5-20 09:14:21

For the first Q, D is the answer.

1) Scientist synthesized a chemical called fullerenes.
2) Naturally occurring fullerenes were found in the mineral shungite.
3) Assumptions: a) The synthesized fullerenes and the naturally ocurring fullerenes in shungite have the same structure. b) If the same structure are found in two compounds, then the two compounds require the same conditions to form.
4) Conclusion: The condition on earth when the mineral shungite was formed could be known.

Answer D says the structure for fullerene in synthetic form are different from that in natural form of shungite. Hence, the assumption a) is wrong. So is the conclusion then.

-- by 会员 sdcar2010 (2012/5/17 9:35:04)

NN, 题干中第一句话写道"Although fullerenes - spherical molecules made entirely of carbon -- were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite." 这里的they指代前面的fullerenes, 也就是spherical molecules，两个不是同一样东西吗？

-- by 会员 mongmong (2012/5/19 13:41:02)

Yeah, they refer to both fullerenes and the spherical molecules. But there might be more than one conditions to form these spherical molecules.

-- by 会员 sdcar2010 (2012/5/19 20:38:24)

Thanks sdcar!

问一道一直都想不通的prep CR问题，请大家帮忙！

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