plunge          move quickly， suddenly and with force

　　poise           be ready， be balanced， self-possession

　　ponderous       heavy， bulky， dull

　　posture         state， attitude； adopt a vain

　　poverty         state of being poor

　　precept         moral instruction

　　precipitate     throw smth violently down from a height

　　precursory      peliminary， anticipating

　　predilection    special liking， mental preference

　　preempt         obtain by preemption or in advance

　　premature       doing or happening smth before the right time

　　presage         warning sign

　　pristine        primitive

　　procrastination keeping on putting off

　　prodigious      enormous， wonderfu