Today, I'd like to show you something which I'm sure you'll find interesting.
今天我要向你们展示一些东西,我相信你们会感兴趣的。
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。