- Omelets are not made without breaking eggs. 有失才有得。
- Once a devil, always a devil. 一次做魔鬼，永远是魔鬼。
- Once a knave, ever a knave. 一朝失足，铸成千古恨。
- Once a man and twice a child. 一次为成人，两度当小孩。
- Once bit, twice shy. 一朝被蛇咬，三年怕草绳。
- Once is no custom. 一次不成立。
- Once on shore, we pray no more. 一旦上了岸，就不再祈祷。
- On earth there is nothing great but man, in man there is nothing great but mind. 在世界上没有一件东西有如人那样伟大，在人之内没有一件东西有如人心那么伟大。
- One barking dog sets all street a-barking. 一狗吠声响，狗吠满街坊。
- One beats the bush, and another catches the birds. 坐享其成。
- One boy is more trouble than a dozen girls. 一个男孩比十二个女孩还要麻烦。
