百年不遇

Explanation: One can not touch a hundred years. Rarely seen or described as a rare opportunity. 　　Usage: Partial official; as the predicate attribute; describe things very difficult to meet 　　Source: Lao She's "Dragon Beard Ditch" Act III: "not to open the General Assembly? Rare, and I work a half day break, the meeting went well." 　　Examples: Not to open the General Assembly? ~, And I work a half day break, the meeting went well. (Lao She's "Dragon Beard Ditch" Act III) Thesaurus:  once in a blue moon, walk with difficulty, fish for a needle in the ocean; look for a needle in a haystack, Impossible and, Sea Fishing, Makes all things easy, bark [bay] at the moon [bay the moon], the sound of footsteps in a deserted valley-a news or a statement which one does not hear often,or a thing that was seldom to found, Rarities, once in thousand years, sth.seldom seen or hardly possible as the iron tree blooms, Hard-won, defy Beyond the bounds of, strength of nine bulls and two tigers,mighty force, doomed petition like asking a tiger for its hide, Leather and Fox plan Antonym Group:  Have no choice but Shengji, Just to stoop and gather Are all, as thick as June blackerries, ubiquitous, overrun, cataclysm crosscurrent, Attracting attention Are all, common and numerous, Even flat-bed truck