- 时不再来 shíbùzàilái irretrievableTime that has passed will never come back.
- 机不可失，失不再来 jībùkěshī, shībùzàilái opportunity knocks onceopportunity knocks but once
- 机不可失，时不再来 jībùkěshī, shíbùzàilái now or neverOpportunity knocks but once.
- 青春不再 qīngchūnbùzài lost youththe state of one's youth having passed and being unable to return
