valuable things offered or given to people who do not appreciate them明珠暗投,對牛彈琴,把貴重的東西送給不識貨的人
英語四級真題
That' s how we found the pearl, actually.
2018年12月四級真題(第二套)聽力 Section B
柯林斯高階英漢雙解學習詞典釋義
N-COUNT
珍珠
A pearl is a hard round object which is shiny and creamy white in colour. Pearls grow inside the shell of an oyster and are used for making expensive jewellery.
If you say that someone is casting pearls before swine, you mean that they are wasting their time by offering something that is helpful or valuable to someone who does not appreciate or understand it.