smooth-tongued /ˈsmuðˈtʌŋd/
  (a.)油嘴滑舌的,花言巧語的
  Smooth-tongued a. Having a smooth tongue; plausible; flattering.
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  smooth-tongued
       adj : artfully persuasive in speech; "a glib tongue"; "a
             smooth-tongued hypocrite" [syn: glib, glib-tongued]