针对最近很多同学就星系的文章提问，特给出一篇具体的文章解析，以供大家参考。同时也欢迎大家就觉得比较难得文章反馈给我，如果共性较多我会在博客和微博详细解读。祝各位好运！

 

    In 1994, a team of scientists led by David Mckay began studying the meteorite ALH84001, which had been discovered in Antarctica in 1984. Two years later, the McKay team announced that ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars. This evidence includes the discovery of organic molecules in ALH84001, the first ever found in Martian rock. Organic molecules—complex, carbonbased compounds—form the basis for terrestrial life.  The organic molecules found in ALH84001 are polycyclic aromatic hydrocarbons, or PAH’s. When microbes die, their organic material often decays into PAH’s.

1994年DM带领的一队科学家开始对在1984年南极洲发现的陨星ALH84001进行研究。两年后，DM宣布ALH84001（科学家们通常同意是源自火星的陨星）包含有力证据证明火星上曾存在生命。证据包括首次在火星岩石发现的有机分子。有机分子——复合碳基化合物是陆地生命的基础。陨星里发现的有机分子叫PAH，即多环芳香碳氢化合物。微生物死后其有机物质经常腐化为PAH。

 

Skepticism about the McKay team’s claim remains, however.  For example, ALH84001 has been on earth for 13,000 years, suggesting to some scientists that its PAH’s might have resulted form terrestrial contamination. However, McKay’s team has demonstrated that the concentration of PAH’s increases as one looks deeper into ALH84001, contrary to what one would expect from terrestrial contamination. The skeptic’s strongest argument, however, is that processes unrelated to organic life can easily produce all the evidence found by McKay’ s team, including PAH’s.  For example, star formation produces PAH’s.  Moreover, PAH’s frequently appear in other meteorites, and no one attributes their presence to life processes. Yet McKay’s team notes that the particular combination of PAH’s in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating form nonbiological processes.

然而，大家还是对DM的观点仍然持怀疑态度。①比如，陨星ALH84001已在地球上13000年，PAH可能是源于陆地污染。但DM辩护道，PAH在陨星里越深越多，这与PAH来源于陆地污染的结果是相反的。②然而，最有力的质疑是，DM发现的证据包括PAH很容易在与有机生命毫不相干的过程中产生。比如，恒星形成产生PAH。另外，PAH经常出现在其他陨星，没人把这归于生命过程。但DM辩护道，陨星里PAH的特殊化合物更类似于腐化机体产生的化合物，而非源于非生物过程。

 

 

Q5: The passage asserts which of the following about the claim that ALH84001 originated on Mars?

A.    It was initially proposed by the McKay team of scientists.

B.    It is not a matter of widespread scientific dispute.

C.    It has been questioned by some skeptics of the McKay team’s work.

D.    It has been undermined by recent work on PAH’s.

E.     It is incompatible with the face that ALH84001 has been on Earth for 13,000 years.

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解析：supporting details

定位the McKay team announced that ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars.

A.    起初是由DM提出来的

B.    没有受到科学广为的争议---正确

C.    已经被DM的一些怀疑者质疑

D.    被有关PAH的作品削弱

E.     与ALH84001已在地球13000年的事实不一致

 

Q6:  The primary purpose of the passage is to

A.    describe new ways of studying the possibility that life once existed on Mars

B.    revise a theory regarding the existence of life on Mars in light of new evidence

C.    reconcile conflicting viewpoints regarding the possibility that life once existed on Mars

D.    evaluate a recently proposed argument concerning the origin of ALH84001

E.     describe a controversy concerning the significance of evidence from ALH84001

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解析：主旨题

Two years later, the McKay team announced that ALH84001, which scientists generally agree originated on Mars, contained compelling evidence that life once existed on Mars.

 

Skepticism about the McKay team’s claim remains, however.

 

A.    描述火星曾经有生命体的可能性的研究方法

B.    纠正鉴于新的证据认为火星有生命体存在的理论

C.    使有关火星是否曾经有生命体的可能性的冲突观点和解

D.    评估最近关于ALH84001起源的观点

E.     描述有关ALH84001证据的重要性的争议---正确

 

Q7:  The passage suggests that the fact that ALH84001 has been on earth for 13,000 years has been used by some scientists to support which of the following claims about ALH84001?

A.    ALH84001 may not have originated on Mars.

B.    ALH84001 contains PAH’s that are the result of nonbiological processes.

C.    ALH84001 may not have contained PAH’s when it landed on Earth.

D.    The organic molecules found in ALH84001 are not PAH’s.

E.     The organic molecules found in ALH84001 could not be the result of terrestrial contamination.

 

解析：信息题

Skepticism about the McKay team’s claim remains, however.  For example, ALH84001 has been on earth for 13,000 years, suggesting to some scientists that its PAH’s might have resulted form terrestrial contamination.

一些科学家看到ALH84001在地球已经13000年，于是提出ALH84001中的PAH可能是来源于陆地污染。换句话说，就是当ALH84001落到陆地时，它并不包含PAH。

A.    多数科学家是相信ALH84001是来源与火星的

B.    尽管文章有谈到PAH是非生物过程中形成的，但他们的观点与ALH84001在地球上的时间长短无关

C.    正确

D.    文章没有暗示出任何科学家都质疑ALH84001中的有机分子不是PAH.

E.     文章指出ALH84001在地球已经13000年，这个证据被一些科学家用来支持PAH是污染形成的

 

补充题目：

Q8: The passage suggests that if a meteorite contained PAHs that were the result of the terrestrial contamination, then one would expect which of the following to be true?

A.    The meteorite would have been on Earth for more than 13,000 years.

B.    The meteorite would have originated from a source other than Mars

C.    The PAH contained in the meteorite would have originated from nonbological processes.

D.    The meteorite would contain fewer PAHs than most other meteorites contain

E.     The PAHs contained in the meteorite would be concentrated toward the meteorite’s surface.

 

解析：应用题

根据文章，一些科学家相信ALH84001在地球已有13000年之久，任何ALH84001当中的PAHs或许来源于地球，即在陆地污染的过程中形成的。同时，文章也谈到，如果陆地污染和ALH84001同时发生，那么这点就与DM的结论——在ALH84001里越深PAH越多——相反，即PAHs应该向ALH84001的外部或表面聚集。

A.    科学家相信13000年是足够长的时间导致陆地污染

B.    文章并没有表明陨星的根源影响陆地PAHs污染的能力

C.    陨星中的PAHs是来源于非生物过程，文章并没有谈到来源与陆地环境的PAHs是否是非生物过程。

D.    文章并没有谈到不同陨星包含不同的PAHs

E.     文章表明如果ALH84001经历陆地污染，那么PAHs会向其表明聚集。

 

Q9: Which of the following best describes the function of the last sentence of the first paragraph?

A.    It identifies a possible organic source for the PAHs found in ALH84001.

B.    It describes a feature of PAHs that is not shared by other types of organic molecules.

C.    It explains how a characteristic common to most meteorites originates.

D.    It suggests how the terrestrial contamination of ALH84001 might have taken place.

E.     It presents evidence that undermines the claim that life once existed on Mars.

 

解析：举例作用题

文章第一段第一句话说到：DM相信ALH84001中发现的PAHs为火星上有生命体提供了强有力的证据。为了解释这一点，文章又说到：PAHs是有机生命体的一种类型，是构成生命体的基础。为了进一步将PAHs和火星上有生命的可能性相联系，第一段最后一句话，表明PAHs的一种来源就是腐化后的微生物。

A. 识别ALH84001中发现的PAHs可能的有机体来源---正确

B. 描述其他有机生命体所不具备的PAHs的特征

C. 解释大多数陨星的特征是怎么由来的

D. 表明ALH84001的陆地污染是怎么产生的

E. 给出证据来削弱火星上有生命体的观点

 

Q10: The passage suggests that McKay’s team would agree with which of the following regarding the PAHs produced by nonorganic processes?

 

A.    These PAHs are not likely to be found in any meteorite that has been on Earth for 13000 years or more.

B.    These PAHs are not likely to be found in any meteorite that originated from Mars.

C.    These PAHs are not likely to be produced by star formation.

D.    These PAHs are not likely to be found in combinations that distinguish them from the PAHs produced by organic processes.

E.     These PAHs are likely to be found in fewer meteorites than the PAHs produced by organic processes.

 

解析：推论题

For example, star formation produces PAH’s. Moreover, PAH’s frequently appear in other meteorites, and no one attributes their presence to life processes.Yet McKay’s team notes that the particular combination of PAH’s in ALH84001 is more similar to the combinations produced by decaying organisms than to those originating form nonbiological processes. 陨星里PAH的特殊化合物更类似于腐化机体产生的化合物，而非源于非生物过程。

A.    PAH不大可能在地球上长达13000年或更长的任何陨星总发现

B.    PAH不大可能在来源于火星的任何陨星中发现

C.    PAH不大可能在陨星形成过程中发现

D.    PAH不大可能在区分于有机过程中PAH产生的化合物中发现

E.     和PAH有机过程相比，PAH不大可能在陨星中发现

 

分析：

A.    DM没有谈到陨星中非有机PAH的存在和陨星在地球上时间的长短有关系

B.    DM没有否定火星陨星中的PAHs是非有机过程这种可能性

C.    DM没有否定PAHs可以在陨星形成的过程中产生

D.    正确，有机过程中产生的PAH化合物可以区分于非有机过程产生的化合物

E.     DM并没有解决陨星中发现非有机PAH的可能性

 

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