knew one's stuff (verb) know by heart: have absolute knowledge
Sinonime: amaranthine, boundless, ceaseless, constant, continual, continuous, countless, deathless, enduring, eternal, everlasting, immeasurable, immortal, incalculable, incessant, indeterminate, infinite, interminable, limitless, measureless, monotonous, multitudinous, never-ending, no end of, no end to, numberless, overlong, perpetual, self-perpetuating, unbounded, unbroken, undivided, undying, unending, unfathomable, uninterrupted, unlimited, unsurpassable, untold, without end