Reading Comprehension
试题详情
文章：
| Line | 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, | |
| (5) | 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 | |
| (10) | molecules—complex, carbon-based compounds— |
| form the basis for terrestrial life. The organic | |
| molecules found in ALH84001 are polycyclic | |
| aromatic hydrocarbons, or PAHs. When microbes | |
| die, their organic material often decays into PAHs. | |
| (15) | 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 PAHs might have resulted | |
| from terrestrial contamination. However, McKay’s | |
| (20) | team has demonstrated that the concentration of |
| PAHs increases as one looks deeper into | |
| ALH84001, contrary to what one would expect from | |
| terrestrial contamination. The skeptics’ strongest | |
| argument, however, is that processes unrelated to | |
| (25) | organic life can easily produce all the evidence |
| found by McKay’s team, including PAHs. For | |
| example, star formation produces PAHs. Moreover, | |
| PAHs frequently appear in other meteorites, and no | |
| one attributes their presence to life processes. Yet | |
| (30) | McKay’s team notes that the particular combination |
| of PAHs in ALH84001 is more similar to the | |
| combinations produced by decaying organisms than | |
| to those originating from nonbiological processes. |
题目：
The primary purpose of the passage is to
选项:
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
答案:
E
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