劍橋詞典buy one get one free : an offer used in shops , in which if you buy one thing, you get another of the same thing for no extra cost 買一送一（商店的一種促銷方法，顧客購買一件商品，就能免費獲得另一件同樣的商品，buy one get one free 的縮寫） 返回 BOGOF