biàn zhēn tàn
nínshìfǒuzàixúnqiú:便衣便衣侦探便衣 便衣侦探gèngduōjiéguǒ...
yīngwénjièshì:
  1.   plain clothes
  2.   a plain-clothes detective
  3.   esp of police officers
  4. n.  fly cop