penetration

n.贯穿；渗透

penalty, penalty area, penalty clause, penalty kick, penance, pence, penchant, pencil, pencil-case, pencil-sharpener, pendant, pendent, pending, pendulous, pendulum, penetrability, penetrable, penetrate, penetrating, penetratingly, penetrative, penguin, penholder, penicillin, peninsula, peninsular, penis, penitence, penitent, penitential, penitentially, penitentiary, penitently, penknife (also `pocket-knife), penmanship, pennant, penniless, pennon, pennorth, Pennsylvania,