2020年成人英语三级考试模拟练习(十四)

2020年成人英语三级考试模拟练习(十四)

In these days of technological triumphs, it is well to remind ourselves from time to time that living mechanisms are often incomparably more efficient than their artificial imitations. There is no better illustration of this idea than the sonar (声纳) system of bats. It is billions of times more efficient and more sensitive than the radars and sonars designed by man.

Of course, the bats have had some 50 million years of evolution to refine their sonar.Their physiological mechanisms for echo location, based on all this accumulated experience, therefore deserve our thorough study and analysis.

To appreciate the precision of the bats' echo locatton, we must first consider the degree of their reliance upon it. Thanks to sonar, an insect - eating bat can get along perfectly well without eyesight. This was brilliantly demonstrated by the Italian naturalist Lazzaro Spallanzani.He caught some bats in a bell tower, blinded them. and released them outdoors. Four of these blind bats were recaptured ,after they had found their ways back to the bell tower,and on examining their stomachs’ contents, Spallanxani found that they had been able to capture and eat flying insects. We know from experiments that bats easily find insects in the dark of night, even when the insects make no sound that can be heard by human ears. A bat will catch hundreds of softbodied silent flying insects in a single hour. It will even detect and chase pebbles ( 卵石 ) tossed ( 向上扔) into the air.

1. According to the author, the sonar system of bats is an example of the idea that_____.

A) this is the age of technological triumphs

B) modern machines are inefficient

C) living mechanisms are often more efficient than man - made machines

D) artificial imitations are always less efficient than living mechanisms

2. The author suggests that the sonar system of bats_____.

A) was at the height of its perfection 50 million years ago

B) is better than man- .made sonar because it has had 50 million years to be refined

C) should have been discovered by man many years ago

D) is the same as it was 50 million years ago

3. Echo location in this article means the_____.

A) location of echoes

B) ability to determine where an echo comes from

C) scientific term for sound waves

D) ability to locate unseen objects by echoes

4. This article was written to illustrate ________.

A) the deficiencies of man - made sonar

B) the dependence of man upon animals

C) that we are living in a machine age

D) that the sonar system of bats is remarkable

5. The following is the main point of the article:

A) A bat will catch hundreds of insects in a single hour

B)There is a perfection in nature which sometimes can not be matched by man's cre ative efforts.

C) The phrase "blind as a bat"is valid.

D) Sonar and radar systems of man are inefficient.

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答案：

1—5 C B D D B

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