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  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.
The discovery of echolocation may help with all of the following EXCEPT______.
选项 A、measuring the depth of the sea
B、distinguishing different kinds of fish
C、bringing the invention of radar
D、varying the size and nature of an object
答案C
解析 事实细节题。本题考查列举处，可用排除法解答。A、B、C在文中都有相关提及。D利用第2段中的varying制造干扰。在原文中，指的是回声因障碍物的不同而不同，而D偷换概念、曲解文意，D中的varying为及物动词．意为“改变”，显然不可能是回声定位的发现带来的功效。
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