With the development of urban construction in recene years, more and more skyscrapers have been set up unceasingly.
随着近年来城市建设的发展,越来越多的摩天大楼不断建起。
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.
我们只要看一看蝙蝠回声定位这一极不寻常的发现,就可以探究一下声音在什么情况下有绝对的实用价值。