While the females don't sing at all,雖然雌鳥完全不會(huì)鳴叫

at all完全； 根本

It's not at all that bad.

這根本沒有那么壞。

I'm not at all sure, actually.

實(shí)際上我根本不能肯定。

the male chicks learn to sing by imitating their fathers,雄性幼鳥卻通過模仿其父來學(xué)習(xí)鳴叫

learn to學(xué)習(xí)

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

我必須學(xué)會(huì)抓住一切機(jī)會(huì)同他見面。

A mountaineer must learn to stand the gaff.

一個(gè)登山運(yùn)動(dòng)員必須學(xué)會(huì)吃苦。

their song developed to no more than a croak.它們的叫聲嘶啞難聽

no more than不過； 僅僅

It's no more than a misunderstanding.

這只是個(gè)誤會(huì)。

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

由車站走到這里只有十分鐘的路程。