As NASA prepares to set twin robots loose on the Martian surface and makes plans to send another in 2007, the agency’s long term goal is clear: Determine whether the red planet does or over did harbor life. `25<;@
But the current search for life is necessarily limited to life as we know it, organisms dependent on liquid water. A SPACE.com reader recently suggested that “we as humans are arrogant, simply believing that any other form of life will be just like us.” w4Hq|N1-Y
Researchers devoted to the search for extraterrestrial (ET) have a similar view. “Scientists” approach to finding life is very Earth-centric”, says Kenneth Nealson, a geobiologist at the University of Southern California. “Based on what we know about life on Earth, we set the limits for where we might look on other planets”, Nealson said. Within that framework, however, there are extreme cases of life on Earth that suggest the range of places to look on frigid Mars. e=# D
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Nealson and his colleagues recently found the most extreme sort of organism in a salty liquid lake under the permafrost of Siberia. The organism, named cryopegella, can exist at colder temperatures than any previously discovered. Nealson’s team figures that if the ice at the polar caps of Mars warmed to liquid water, organisms like cryopegella could h***e awakened and repaired any damage that might have occurred to their various cellular components. That does not mean there are necessarily dormant microbes within the ice caps of Mars. But it does suggest a broader range of potential cradles for life. PN J&{4wY
Other researchers agree, and a host of so-called “extremophile” discoveries on Earth in recent years indicate the polar regions of Mars might be prime hunting grounds. As on Earth, organisms there might be slathered in natural antifreeze or be able to go dormant for tens of thousands of years. Waiting for a brief thaw, their moment in the Sun. 5L7 nEia'
Meanwhile, scientists recognize that there could indeed be life elsewhere in the universe that does not require water. And some astrobiologists are trying to explore the possibilities. But it is a tough problem to approach. In looking for “life as we don’t know it”, it’s hard to even imagine what to expect. 6N Ogi
Life might or might not exist on Mars. If there are critters there, they might or might not be like bacteria on Earth. In laboratory conditions, scientists in 2001 were able to get one-celled organisms to incorporate an amino acid---a fundamental building block of life---that no other known life uses. The discovery borders on the creation of artificial life, experts said. It also suggests that ET might operate by entirely different rules than those we’re used to. 211T}a
If life on Mars is fundamentally different from what scientists understand life to be, then current spacecraft and others in the works may well not recognize what’s right under their mechanical noses. &oZU=CN
46. According to the text, we human beings are arrogant because 9@Cu5U]
[A] we can send robots to Mars. +4qR5(W
[B]we are searching ET in the outer space. 8090+ ( U
[C] we assume that life is all humanlike. Ne3YhCC >
[D] we believe we are the most intelligent life. .Tw:Y,G
47. According to Kenneth Nealson, scientists’ current approach to finding life is IQd~`
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[A] limited. [B]costly. [C] centralized. [D] earthly. Be\@n xV[
48. Nealson’s team’s discovery of extreme cases of life on Earth suggests that ]j*uD317
[A] there might be life on Mars that still remains dormant. 8B!QqLqK
[B]there might be ET in the universe that is like human beings. u2 fp~.'P
[C] there might be life that is beyond the range of our current search. ~GJ;;v1b2
[D] there might be ET elsewhere in the universe that does not require water. X -=M>H^
49. The purpose of the author mentioning scientists’ laboratory creation in 2001 is to emphasize the idea that Dwr" -
[A] it is hard to imagine what ET is really like. KCp9P2kv.
[B]life might or might not exist on Mars. Z?&ZgaSz
[C] it is possible to create artificial life. yVK l%GO
[D] Martians may live by entirely different rules. ,S`F xJcE
50. What is the best title of the text? eZh
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[A] Does Mars Harbor Life? ^;[_CF _
[B]If We Find ET, Will We Know It? cc1M9kVi
[C] Will the Twin Robots Live Up to Us? COBjJ3
[D] Why Search ET As We Don’t Know It? qM 2m !
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感觉做起来不难，但答案很多模拟两可。大家对照一下答案，我的答案是：CACDD。 大家交流一下。
