preemptv.以优先购买权获得；先占；(桥牌中)先发制人地叫牌；优先；取代preemptible program抢占式程序preemptive priority抢先优先权,先抢优先Preemptive analgesis超前镇痛Preemptive multitask抢占式多任务preemptive petri net抢占式时间Petri网preemptive algorithm抢先算法preemptive real task实时抢占多任务preemption of lessee承租人优先购买权preemption threshold抢占阈值preemptive analgesia超前镇痛； 先发镇痛