江苏省一般高等学校“专转本”统一考试大学英语第 I 卷(共 100 分)Part I Reading Comprehension (共 40 分)Passage oneUnder proper conditions, sound waves will be reflected from a hillside or other such obstruction
Sound travels at the rate of about one-fifth of mile per second
If the hill is eleven hundred feet away, it takes two seconds for the sound to travel o the hill and back
Thus, by timing the interval between a sound and its reflection (the echo), you can estimate the distance to an obstruction
During word war 2 the British used a practical application of this principle to detect German planes on their way to bomb London long before the enemy was near the target
They used radio waves instead of sound waves, since radio waves can penetrate fog and clouds
The outnumbered Royal Air Force (RAF) always seemed to t