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  3. It is hard to track the blue whale, the ocean’s largest creature, which has almost been killed off by commercial whaling and is

It is hard to track the blue whale, the ocean’s largest creature, which has almost been killed off by commercial whaling and is

admin2011-03-01  23
问题    It is hard to track the blue whale, the ocean’s largest creature, which has almost been killed off by commercial whaling and is now listed as an endangered species. Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior.
   So biologists were delighted early this year when, with the help of the Navy, they were able to track a particular blue whale for 43 days, monitoring its sounds. This was possible because of
the Navy’s formerly top-secret system of underwater listening devices spanning the oceans.
   Tracking whales is but one example of an exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies.
   Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption (爆发) for the first time and that they plan similar studies.
   Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures.
   The speed of sound in water is roughly one mile a second-slower than through land but faster than through air. What is most important, different layers of ocean water can act as channels for sounds, focusing them in the same way a stethoscope (听诊器) does when it carries faint noises from a patient’s chest to a doctor’s ear. This focusing is the main reason that even relatively weak sounds in the ocean, especially low-frequency ones, can often travel thousands of miles.
It can be inferred from the passage that______ .
选项 A、new radio devices should be developed for tracking the endangered blue whales
B、blue whales are no longer endangered with the use of the new listening system
C、opinions differ as to whether civilian scientists should be allowed to use military technology
D、military technology has great potential in civilian use
答案D
解析 本题属于推理性问题。这个问题我们也只有对比四个选项从中选出一个比较好的。首先我们可以排除A选项new radio devices should be developed for tracking the endangered blue whales和B选项blue whales are no longer endangered with the use of the new listening system，在前面的分析中我们已经说过，蓝鲸在本文中只是作为一个例子出现的，不可能成为文章的主题或推论的对象，
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