Backactor
反铲挖土机
🗣️ 情景例句
Your family or the public?
你的家人还是公众
A friend without faults will never be found.
没有缺点的朋友是永远找不到的。
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。