千载难逢: it happens only once in a thousand years.; difficult to meet in a thousand years; only once in a lifetime; occurring only once in a thousand years; very rare; once in a blue moon 短语和例子千载难逢
难得: 1.(不易得到) hard to come by; rare 短语和例子难得的好机会 a rare chance; 这种草药很难得。 this medicinal herb is hard to come by.2.(不常发生) seldom; rarely 短语和例子她难得到这里来。 she seldom comes here