per·ma·nence /ˈpɝmənən(t)s, ˈpɚ/
  永久,持久
  Per·ma·nence Per·ma·nen·cy n.  The quality or state of being permanent; continuance in the same state or place; duration; fixedness; as, the permanence of institutions; the permanence of nature.
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  permanence
       n : the property of being able to exist for an indefinite
           duration [syn: permanency] [ant: impermanence]