While the females don't sing at all,虽然雌鸟完全不会鸣叫

at all完全； 根本

It's not at all that bad.

这根本没有那么坏。

I'm not at all sure, actually.

实际上我根本不能肯定。

the male chicks learn to sing by imitating their fathers,雄性幼鸟却通过模仿其父来学习鸣叫

learn to学习

I must learn to snatch at every chance to meet him.

我必须学会抓住一切机会同他见面。

A mountaineer must learn to stand the gaff.

一个登山运动员必须学会吃苦。

their song developed to no more than a croak.它们的叫声嘶哑难听

no more than不过； 仅仅

It's no more than a misunderstanding.

这只是个误会。

It is no more than ten minutes' walk from the station.

由车站走到这里只有十分钟的路程。