fifties (n.) fifties n.五十年代；五十岁fifthwheel n.半拖车接轮(转向轮)fifths adj.第五fifthly adv.第五；第五地fifth-wheel 半拖车接轮fifth-generation adj.第五代的fifth wheel instrument 五轮仪fifth wheel 第五个轮子；备用轮；多余的人fifth republic movement fifth part fifth grade 五年级fifth crusade fifth cranial nerves fifth cranial nerve fifth columnism fifth column (n.) fifth column n. 第五纵队fifth amendment （美国宪法修正案）第五条fifth alarm [管理学]五级火警