神不知鬼不觉
      Explanation: Means acting secretive, unknown.
      Usage: Complex sentence; for clause; describe things done very secret
      Source: Yuan Anonymous "enemy creditors" second off: "It troubles mysteriously, days high to thick."
      Examples: Yao Xueyin "Rereading," Volume I Chapter 14: "Rereading and Liu Zongmin so ~ to leading a team of over a Luonan ambush in the eastern foot of the mountain forests in the Mountain."
  • Thesaurus:  clever Guiltless Ghost nobody knows