Cast Pearls before Swine

（此处pearl为及物动词，意为用珠状物装饰） cast pearls before swine 把珍珠丢在猪面前； 明珠暗投； 对牛弹琴 He who would search for pearls must dive below. 欲寻珍珠就要潜到水里； 不入虎穴，焉得虎子。