防不胜防
fáng​bù​shèng​fáng

impossible to defend against

  1. 防 fáng verb
    to guard against
    To take precautions against; to prevent or be on the lookout for something undesirable
  2. 不 bu particle
    [potential]
    Used between a verb and its result to show that the action cannot achieve that result; used as the negative form of the 得 de potential construction
  3. 胜 勝 shēng verb
    to bear
    (bound form) to be able to bear; to sustain; to be equal to a task
  4. 防 fáng verb
    to guard against
    To take precautions against; to prevent or be on the lookout for something undesirable