共用题干 第一篇In the dark night of the desert,a group of U.S.Air Force scientists is testing a new device for a missile to target.Designed to seek out the heat of an enemy aircraft engine,it is now going through its paces by tracing the movement of a flashlight waving thirty feet away in the darkness.A hundred yards away,unseen by the man,a rattlesnake sliding between the stones senses a patch of warmth. Although the snake's mechanism is small enough to be packed into a head the size of a nut,it can detect a change in temperature of one-thousandth of a degree.With a sound the snake closes in and strikes for the kill.Whenever we look in the animal world we find the same story.Almost anything that man can do,nature has already done better. So,it is for the purpose of learning from nature that a new science called bionics has grown up.Its aim is to find out how animal's instruments work so that man can copy them for his own purpose.Imagine being able to know a friend several miles off by his smell. Male silk moths can do this. Their antennae are so sensitive to the chemical odor of female moths that they can detect their presence by picking up only one molecule of the chemical.Even with their most sensitive instruments, human cannot approach this perfection.Studying beetle's eyes has already paid off. A group of scientists in Germany found that a beetle can accurately measure with its eyes the speed of moving background.After finding out how a beetle accomplishes this scientists built a machine that operated on the same principle.This instrument is able to determine the ground speed of moving aircraft with a high degree of accuracy. The writer compares the rattlesnake with a missile in order to______.
A.show the deadliness of the missile B.demonstrate what bionics is C.show that man is wiser than nature D.demonstrate that a rattlesnake is dangerous正确答案B
