Through thick and thin, they have always been my precious team mates, advisers, and above all, friends.
我们同甘共苦,亲如伙伴,他们是我的军师,更是我的朋友。
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。