【课文】
First listen and then answer the following question.
听录音，然后回答以下问题。
In what way does echo-location in bats play an utilitarian role?
Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echo-location in bats to see a case in which the voice plays a strictly utilitarian 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 in the vicinity ofa wall or a mountainside, an echo will come back. The further off this solid obstruction, the longer time will elapse for the return of the echo. A sound made by tapping on the hull 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 apparatus, 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 apparatus, it is now possible not only to locate a shoal but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
It has been found that certain bats emit squeaks and by receiving the echoes, they can locate and steer clear of obstacles -- or locate flying insects on which they feed. This echo-location in bats is often compared with radar, the principle of which is similar.
MAURICE BURTON Curiosities of animal life
【New words and expressions 生词和短语】
bat n. 蝙蝠
strictly adv. 明确地
utilitarian adj. 实用的
appreciation n. 理解
obstruction n. 障碍物
elapse v. 消逝
hull n. 船体
interval n. 间隔
receipt n. 收到
apparatus n. 仪器
shoal n. 鱼群
herring n. 鲱鱼
cod n. 鳕鱼
squeak n. 尖叫声
【课文注释】
1.Not all sounds made by animals serve as language，动物发出的声音不全是作语言交际。此句采用了部分否定，即不是否定所有的动物，而只是一部分。
serve as，作……之用。
例句：May this punishment serve as a warning to you.
你要以此为鉴戒。
serve the purpose，起作用、 能解决问题。
例句1：It"s not exactly what I wanted but it will serve my purpose.
这个跟我想要的不太一样，但也算可以。
例句2：Theories serve a dual purpose.
理论有双重效果。
2.play a role/part in，在……方面起作用。
例句：Parents play significant roles in educating a child.
父母在教育孩子方面有着举足轻重的作用。
take part/role in，参加，参与。
例句：We all had to take part in the training run, with nobody excepted.
我们大家都得参加跑步训练，无人例外。3.in the vicinity of，在……附近。
这是比较正式、书面的表达法，和near是同一个意思。
例句：All the ships in the vicinity of the crash joined in the search for survivors.
撞船事故发生地区的所有船只都参加了搜寻幸存者的工作。
另外，vicinity也可以表达大约、大概。
例句：This city has a population in the vicinity of 100000.
这座城市有10万左右的人口。
4.So was born the echo-sounding apparatus，这样就诞生了回声探测仪。这是一个倒装句，主要是为了避免因主语过长而使全句失去平衡，同时也为了使apparatus的定语now in general use in ships紧挨着名词。
in general use，普遍使用。
generally speaking，通常说来。
in general terms，总的说来。
5.vary，变化。
vary with sth，随……变化而变化。
例句：Prices vary with the seasons.
物价随季节而变动。
名词：variety，种类。
形容词①：variable，可变的，多变的。
形容词②：various，各种各样的。
6.steer clear of，避开
If you steer clear of someone or something, you deliberately avoid them.
例句：Since then they have tended to steer clear of contentious issues.
从那时起，他们总想方设法避开有争议的问题。
【参考译文】
动物发出的声音不都是用作语言交际。我们只要看一看蝙蝠回声定位这一极不寻常的发现，就可以探究一下声音在什么情况下有绝对的实用价值。
要透彻理解这句话的意义，我们应先回顾一下人类最近的几项发明。大家都知道，在墙壁或山腰附近发出的喊声，就会听到回声。固体障碍物越远。回声返回所用时间就越长。敲打船体所发了的声音会从海底传回来，测出回声间隔的时间，便可算出该处海洋的深度。这样就产生了目前各种船舶上普遍应用的回声探测仪。任何固体者反射声音，反射的声音因物体的大小和性质的不同而不同。鱼群也反射声音。从测定海深到测定鱼群，这一进展比较容易。根据经验和改进了的仪器，不仅能够确定鱼群的位置，而且可以根据鱼群回声的特点分辨出是鲱鱼、鳕鱼，这是人们所熟悉的其他鱼。
人们发现，某些蝙蝠能发出尖叫声，并能通过回声来确定并躲开障碍物，或找到它们赖以为生的昆虫。蝙蝠这种回声定位常常可与雷达相比较，其原理是相似的。
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