Definition
To do something unnecessary or redundant; to do something pointless because it is already abundant in the place or with the person you are giving it to.
多此一舉
Trying to teach him how to use a computer is like carrying coals to Newcastle; he's a computer expert.
試圖教他如何使用電腦就像是把煤運到紐卡斯爾；他已經是電腦專家了。
Selling water to the Amazon rainforest is like carrying coals to Newcastle; water is abundant there.
向亞馬遜雨林賣水就像是把煤運到紐卡斯爾；那裡的水資源非常豐富。
Buying him a book on photography would be like carrying coals to Newcastle, as he already has dozens.
給他買一本攝影書就像是把煤運到紐卡斯爾，因為他已經有幾十本了。