small birds in general (swallows and sparrows)

(literary) used in rhetorical questions to mean "how could anyone know" or "who's to say"; often used in the idiom 塞翁失马，焉知非福 sài​wēng​shī​mǎ​yān​zhī​fēi​fú

(literary) a swan; any large bird like a swan or wild goose

Connects a describing word or phrase to the noun it describes, similar to 的 de but used in formal or literary writing.

aspiration; ideal; ambition; the will to achieve something