GWD3-Q7 求教

onlyspirit

原文：

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.

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.

题目

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.

个人看法：
正确选项是C。个人理解B是更佳答案，虽然C是可以推导出的结论，但科学家们反对McKay Biological Process的观点，支持terrestrial contamination的观点，并且13000年的时间terrestrial 的影响大于 Biological，因而nonbiological process更为合适。
大家怎么看？

吉曼特托夫

我也感觉是B，既然是由于terrestrial contamination，那么不就是nonbiological process了嘛？求NN解答

onlyspirit

吉曼特托夫 发表于 2014-9-19 17:16
我也感觉是B，既然是由于terrestrial contamination，那么不就是nonbiological process了嘛？求NN解答 ...

现在终于弄清楚这道题目了。
Non biological Process是第二段的另一个论点，不可以混淆。

halamadrid0928

应该这么理解吧，terrestrial contamination就是biological process，所以B刚好和科学家们的观点相反