2. 外语
  3. Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echolocation (回声定位

Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echolocation (回声定位

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问题     Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echolocation (回声定位) in bats to see a case in which the voice plays a strictly practical role.
    To get a full appreciation of what this means we must turn first to some recent human inventions. Everyone knows that if he shouts near a wall or a mountainside, an echo will come back. The further off this solid obstacle, the longer time it will take for the return of the echo. A sound made by tapping on the main body of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps and the receipt of the echoes the depth of the sea at that point can be calculated. So was born the echo-sounding equipment, now in general use in ships. Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step from locating the sea bottom to locating a shoal of fish. With experience, and with improved equipment, it is now possible not only to locate fish but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
    A few years ago it was found that certain bats emit squeaks (吱吱声) and by receiving the echoes they could locate and steer clear of obstacles—or locate flying insects on which they feed. This echolocation in bats is often compared with radar, the principle of which is similar.
As is discussed in the passage, the squeaks of bats can be functionally compared with______.
选项 A、human languages
B、a mountainside
C、a shoal of fish
D、taps on a ship
答案D
解析 推理判断题。根据最后一段可知，蝙蝠发出吱吱声可以探测障碍物的距离，而第2段也指出轻敲船体可测知海底的距离，因此在功能上，D与蝙蝠的吱吱声相同。A中的human languages在文中未提到；B和C在文中各自的例子中充当的都是障碍物的角色，因此都不正确。
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