机不可失，时不再来
jī​bù​kě​shī​shí​bù​zài​lái

opportunity knocks but once

  1. 机不可失 機不可失 jī​bù​kě​shī
    don't let an opportunity slip by
    (idiom) good opportunities are hard to come by and must not be missed; no time to lose; now or never
  2. ， shí
    non-Chinese
  3. 时不再来 時不再來 shí​bù​zài​lái
    opportunity knocks but once
    Time or opportunity once lost will never come back again; often used to encourage someone to seize the moment, and frequently paired with 机不可失 jī​bù​kě​shī.