B) is better than man-made sonar because it has had 50 million years to be be refined
C) should have been discovered by man many years ago
D) is the same as it was 50 million years ago
18. 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
19 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
20. 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 mans creative efforts.
C) The phrase blind as a bat is valid.
D) Sonar and radar systems of man are inefficient.
Questions 16 to 20 are based on the following passage:
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 system of bats. It is billions of times more efficient and more sensitive than the radars and sonars designed by man.
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