principal act主要行为principaladj.主要的；首要的n.本金；资本；校长；主角；委托人；主犯principal point of photograph象主点principal professionalization校长专业化principal compoenent analysis大黄principal part of recognition认识主体Principal Embarkation Officer登船带队军官(英国)principal diagonal polynomial主对角多项式principal vibration direction主变更方向principal linear optimization最优线性化principal anti-automorphism主反自同构principal congruence subgroup脂余子群