impermanent [ɪmˈpɜ:rmənənt]

例句:

• We are reminded just how small and how impermanent we are.
  它让我们意识到我们有多么渺小，我们的生命是何其短暂。
  
• Everything impermanent as change is the only constant in nature.
  凡事变幻无常,唯一不变的自然定律就是“变”!
  
• The mind , in fact , is as empty , as impermanent, and as transient as a dream.
  我们的心其实是空幻的、无常的, 如梦般空虚短暂.
  
• More recently, Facebook has stapled on new features to its messaging app, like calling, voice mail and impermanent texts.
  来自WSJ