transitory       
adjective  formal uk/ˈtræn.zɪ.tər.i/ us/ˈtræn.sə.tɔːr.i/
 短暂的,转瞬即逝的
lasting for only a short time
  the transitory nature of life 生命转瞬即逝的本质 
 Synonyms: brief (SHORT IN TIME)ephemeralevanescent fleetingfugitive (TEMPORARY) momentarypassing short-livedtransient