impregnable

adj. 攻不破的，征服不了的

impostor, imposture, impotence, impotent, impotently, impound, impoverish, impoverished, impoverishment, impracticability, impracticable, impracticably, impractical, impracticality, impractically, imprecation, imprecise, imprecisely, imprecision, impregnability, impregnably, impregnate, impresario, impress, impress...on, impressed, impression, impressionability, impressionable, impressionism, impressions, impressive, impressively, impressiveness, imprimatur, imprint, imprinting, imprison, imprisonment, improbability,