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  3. Despite the ubiquity of computer technology, most people are unaware that Line computers exist in two mutually exclusive, disti

Despite the ubiquity of computer technology, most people are unaware that Line computers exist in two mutually exclusive, disti

admin2012-01-15  51
问题       Despite the ubiquity of computer technology, most people are unaware that
Line  computers exist in two mutually exclusive, distinct categories: analog and digital.
      We are most familiar with digital computers, such as laptops. On the one hand,
      digital computers process information using a binary number system that allows
(5)   them to calculate numbers in an accurate and exact manner. Analog computers,
      on the other hand, do not calculate per se; they measure and respond to a
      continuously changing input.
            Simple analog computers, called astrolabes, were first developed by the
      Greeks to solve problems in astronomy. The devices proved very popular and
(10)  soon spread throughout the Roman world. By the 10th century, Muslim scholars
      had developed the astrolabe into a sophisticated mechanical device capable of
      calculating solutions to problems not only in astronomy, but also in astrology,
      navigation, surveying, and timekeeping.
           Modern scientific opinion was that the ancient Greeks had been
(15)  technologically unable to produce a similarly sophisticated computer, until a
      discovery was made just over a century ago. In 1900, divers discovered the wreck
      of a merchant ship, possibly dating back to 150 BCE, off the coast of the Greek
      island Antikythera. In the wreckage, they found the remains of a complex device
      apparently a thousand years ahead of its time.
(20)       Made of metal, this device, known as the Antikythera mechanism, is
      approximately the size of a shoebox. At the time of its discovery, it was in terrible
      shape, having been underwater for so long. Its pieces had merged into a broken
      mass and experts could discern only that it had something to do with astronomy.
      Thanks to a combination of advanced imaging methods and X-ray computer
(25)  tomography, however, scientists have since discovered much more.
           Originally, the mechanism had at least 30 bronze gears with as many as 225
      hand-cut triangular teeth. It had three main dials, one on the front and two on the
      back, respectively marking the astronomical divisions of the Egyptian calendar,
      the Metonic cycle, and the Saros cycle. Each dial had subdials for greater
(30)  specificity. For example, the front dial contained a smaller dial that could be
      adjusted to account for leap years. There were also hands and gearing to account
      for the movements of the planets.
           While the workings of the device are now fairly well understood, researchers
      are still puzzled by the reason it was made. Some postulate that it, like later
(35)  astrolabes, was used to create astrological charts, or to set feast days, or even to
      adjust the lunar and solar calendars. Others have thought it was a curiosity made
      solely for display. The device’s relatively small size and the inclusion of a 3,000
      character "user’s manual" suggest that the mechanism was created to be portable
      and functional, but scientists are no closer to knowing for sure and can only
(40)  wonder at the purpose of its superb design.
The author mentions that the front dial of the Antikythera mechanism contained a smaller, adjustable dial (line 30) most probably in order to
选项 A、illustrate the complexity of the mechanism
B、describe exactly how the mechanism worked
C、emphasize the importance of leap years in the study of astronomy
D、argue that the mechanism was used only for very specific tasks
E、allow readers to imagine what the device looked like
答案A
解析
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