perpetual          
adjective uk/pəˈpetʃ.u.əl/ us/pɚˈpetʃ.u.əl/
 永久的,永恒的;长期的
continuing for ever in the same way
  They lived in perpetual fear of being discovered. 他们长期生活在恐惧中,担心被发现。 
 He has hard, cold eyes and his mouth is set in a perpetual sneer. 他双眼又凶又冷,嘴角总是挂着一丝蔑笑。 
 a perpetual student 终生学习者 
  不断重复的;永无休止的
often repeated
  perpetual vandalism 对公共财物不断的蓄意破坏