pendulum

n.钟摆

penal law, penal servitude, penalization, penalize, penalize, penalise, penally, penalty, penalty area, penalty clause, penalty kick, penance, pence, penchant, pencil, pencil-case, pencil-sharpener, pendant, pendent, pending, pendulous, penetrability, penetrable, penetrate, penetrating, penetratingly, penetration, penetrative, penguin, penholder, penicillin, peninsula, peninsular, penis, penitence, penitent, penitential, penitentially, penitentiary, penitently, penknife (also `pocket-knife),