/feɪz ||; fez/verbphase sth in to introduce or start using sth gradually in stages over a period of time 分阶段引进；逐步实施: The metric system was phased in over several years. 公制分数年逐步推行。 phase sth out to stop using sth gradually in stages over a period of time 分阶段淘汰，逐步取消: The older machines are gradually being phased out and replaced by new ones. 旧的机器正逐渐淘汰，由新的机器取代。