If something is three-quarters full, it contains three out of the four quarters of the amount or number it can contain. If something is three-quarters empty, it contains a quarter of the amount or number it can contain.
双语例句
例： We were left with an open bottle of champagne three-quarters full.
有人留给我们一瓶打开过的、还剩3/4的香槟酒。
例： The stadium was three-quarters empty when the match began.
比赛开始时，该体育馆有四分之三空座。