2. 外语
  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 n

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

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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 【S1】______ sightings are too unreliable to give real 【S2】______ into its behavior.
    So biologists were delighted early this year when with the help of the Navy, they were able to 【S3】______ a particular blue whale for 43 days, monitoring its sounds. This was possible because of the Navy’s formerly top-secret system of under water 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 【S4】______ its global network of underwater listening system built over the decades to track the ships of 【S5】______ enemies.
    Earth scientists announced at a news conference recently that they had used the system for closely 【S6】______ a deep-sea volcanic eruption (爆发) for the first time.
    The speed of sound in water is 【S7】______ one mile a second—slower than through land but faster than through air. What is most important, different 【S8】______ of ocean water can act as channels for sounds, focusing them in the same way a stethoscope (听诊器) does when it 【S9】______ faint noises from a patient’s chest to a doctor’s ear. This focusing is the main reason that even 【S10】______ weak sounds in the ocean, especially low-frequency ones, can often travel thousands of miles.

A) layers            B) roughly           C) observation          D) monitoring
E) visual            F) uncover           G) discover             H) carries
I) relatively        J) visible           K) insight              L) examining  
M) potential         N) considerably      O) track
【S7】
选项
答案B
解析 从结构上判断应选一个副词，来修饰后面的数词，三个副词中表示“大约，大概”的只有roughly，故B为正确答案。
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大学英语四级

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