千载一时[遇] [- - yì shí]a golden opportunity; an extremely rare chance [opportunity]; a (very) rare opportunity; only once in a thousand years; (A thing like that) only happens once in a blue moon; a time of a thousand years; the chance of a lifetime:
•¶ 不要糟踏这样一个千载一时[遇]的机会。 Don't waste such a golden opportunity.