ten·a·ble /ˈtɛnəbəl/
  (a.)可守的,可主張的,有條理的,成立的
  Ten·a·ble a.  Capable of being held, maintained, or defended, as against an assailant or objector, or against attempts to take or process; as, a tenable fortress, a tenable argument.
  If you have hitherto concealed his sight,
  Let it be tenable in your silence still.   --Shak.
     I would be the last man in the world to give up his cause when it was tenable.   --Sir W. Scott.
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  tenable
       adj : based on sound reasoning or evidence; "a reasonable
             argument"; "well-founded suspicions" [syn: well-founded]