2. 外语
  3. Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why th

Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why th

admin2013-03-11  67
问题     Noses have their advantages. They’re cute, they’re versatile, and they’re small enough to be carried around. Which may be why the artificial odor detectors that engineers have been building since the 1950’s to try to mimic the olfactory(嗅觉的) abilities of our built-in sensors have taken so long to find their way to the market--and then, in most cases, have flopped(失败).
    But things are finally looking up for the electronic nose. Thanks to advances in chip technology and pattern-recognition techniques, increasingly tiny sniffers (嗅探器) are beginning to live up to their moniker (模仿者)- Today e-noses are being tested for everything from disease detection to disaster prevention, and lower-prices models are starting to come to the market including an $ 8,000 device called the Cyranose 320 being introduced this week by Cyrano Sciences of Pasadena, Calif.
    Like our proboscises(长鼻子), e-noses are only as good as their sensors, and all of them operate on oiliness(油质)--rather than to the molecule itself. Working together, the receptors can generate unique principles remarkably similar to those of a real nose. Humans detect odors with up to 650 types of receptors found on cells high up in the nasal passages, somewhere between our eyebrows. How the nose works is still something of a mystery, but it is believed that each receptor responds to a subtle characteristic of a molecule that carries odor--its peculiar shape, say, or degree of "smell prints" of a wide variety of odors, which are then parceled off to the brain and stored.
    In e-noses, chemical sensors replace the body’s cellular receptors, and microprocessors substitute for the brain. "What limits these devices is how well the sensors are doing," explains Nathan Lewis, the Caltech chemist who helped invent the sensor technology licensed by Cyrano and who has since continued his research independently. He compares the power of e-noses to the resolution of computer monitors: "Are you seeing the world in eight shades of gray or in 16 million colors?"
The purpose of the writer in writing the passage is ______.
选项 A、to give an objective account of the e-nose
B、to question the wide use of the e-nose
C、to discuss the advantages of the e-nose over the human nose
D、to encourage the introduction of the e-nose to the market at a lower price
答案A
解析 主旨题。该题问及这篇文章的写作目的。对于此类的科(普)技文章，考生可以判定客观性 (objective)是惟一的标准，从而做出正确的判断。答案为A“对电子鼻做一客观报道。”
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大学英语四级

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