乘虚而入

to enter by exploiting a weak spot (idiom); to take advantage of a lapse

surname Cheng

to ride / to mount / to make use of / to avail oneself of / to take advantage of / to multiply (math.) / Buddhist sect or creed

four horse military chariot (archaic) / four (archaic) / generic term for history books

old variant of 乘[cheng2]

(archaic) four horse military chariot / (archaic) four / generic term for history books

to take advantage of weakness

emptiness / void / abstract theory or guiding principles / empty or unoccupied / diffident or timid / false / humble or modest / (of health) weak / virtual / in vain

and / as well as / and so / but (not) / yet (not) / (indicates causal relation) / (indicates change of state) / (indicates contrast)

to enter / to go into / to join / to become a member of / to confirm or agree with / abbr. for 入聲|入声[ru4 sheng1]