qīng chūn bù zài
lit. one's youth will never return
to make the most of one's opportunities (idiom)
shí bù zài lái
Time that has passed will never come back. (idiom)
jī bù kě shī , shí bù zài lái
Opportunity knocks but once. (idiom)
jī bù kě shī , shī bù zài lái
opportunity knocks but once (idiom)
jī bù kě shī , shí bù zài lái
Opportunity knocks but once. (idiom)