下陷

to subside / subsidence

down / downwards / below / lower / later / next (week etc) / second (of two parts) / to decline / to go down / to arrive at (a decision, conclusion etc) / measure word to show the frequency of an action

pitfall / trap / to get stuck / to sink / to cave in / to frame (false charge) / to capture (a city in battle) / to fall (to the enemy) / defect