Lesson 7 Bats 第七课蝙蝠
by MAURICE BURTON from Curiosities of animal life
7-1. 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.
译文动物发出的声音并不都起语言作用。我们只需举发现蝙蝠的回声定位这个不同寻常的例子，就能知道声音起着极其实用的作用。
讲解Not all sounds…这里否定的是其中一部分，叫部分否定句。all，every，both，always等用于否定结构时不是全部被否定，而是表示其中的一部分被否定。而且英语多半将not置于谓语中。
例如： All is not a gold that glitters.（即Not all that glitters is gold.） 闪闪发光物，未必尽黄金。
Every one cannot write novels.（即Not every one can write novels.） 不是所有的人都能写小说。
I don’t like both of the novels.（即I like only one of the two novels.） 这两本小说我不是都喜欢。
plays a strictly utilitarian role直译为“扮演绝对实用的角色”，可译为“发挥绝对实用的作用”。
单词和短语
turn to：求助于；求教于；查阅（to try to get help, advice, or sympathy from sb.），
例如： You can always turn to me for help. 你随时可以来找我帮忙。
utilitarian：实用的（intended to be useful and practical rather than attractive or comfortable），
例如： A good cloth coat is more utilitarian than a fur one. 一件优质的布外衣要比一件毛皮外衣更有用。
另掌握utilitarianism（功利主义）一词。
7-2. To get a full appreciation of what this means we must turn first to some recent human inventions.
译文要透彻理解这句话的含义，我们应先回顾人类最近的几项发明。
讲解to get a full appreciation of what this means作目的状语，修饰turn。不定式作状语放在句首，比放在后边更要正式，语气较重。what this means是名词性从句，作of的宾语。this指上句we have only to turn…plays a strictly utilitarian role。
单词和短语
appreciation：估价；评价；鉴别（an understanding of the importance or meaning of sth），
例如： They are mistaken in their appreciation of the country’s economic conditions. 他们对国家经济形势的判断是错误的。
have a keen appreciation of a joke 能深刻领会一句笑话的妙处
appreciation的动词形式为appreciate，形容词形式为appreciative。
7-3. Everyone knows that if he shouts in the vicinity of a wall or a mountainside, an echo will come back.
译文大家都知道，如果有人在墙壁或半山腰附近发出喊声，他就会听到回声。
单词和短语
in the vicinity (of sth.)：（在……）附近；（与……）接近（in the area around a particular place），
例如： a mansion in the vicinity of the lake 湖滨大厦
His income is in the vicinity of $50,000 他每年的收入将近五万美元
7-4. The further off this solid obstruction, the longer time will elapse for the return of the echo.
译文固体障碍物越远，回声返回所用时间就越长。
讲解obstruction后省略了is。for the return of the echo作time的定语。
单词和短语
obstruction：阻塞物；障碍（物）（when sth blocks a road, passage, tube etc, or the thing that blocks it），obstruction的动词形式为obstruct。
elapse：（时间）消逝，过去（if a particular period of time elapses, it passes），
例如： Five years elapsed before he returned. 过了5年他才回来。
7-5. 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.
译文敲打船体所发出的声音会从海底反射回来，测出回声与原声间隔的时间就可算出该处海洋的深度。
单词和短语
receipt:收到，接到（when sb. receives sth.），
例如： We are awaiting the receipt of further information. 我们正在等着接获进一步的信息。
receipt另一常见意为“收据，发票”，receipt的动词形式为receive。
interval：（空间、时间上的）间隔；间距；间隙；空隙（the period of time between two events, activities, etc），
例如： an interval of 30 years 30年的间隔
the interval between a lightening flash and the following thunder 电闪与随后雷鸣之间的间歇
an interval of 10 metres between posts 柱间10米的距离
She has intervals of freedom from worry. 她间或也有摆脱烦恼之时。