为什么是a cup of tea 不是 a cup tea

为什么是a cup of tea 不是 a cup tea a cup of tea ? over a cup of tea ( ) a cup of tea ,please. a cup of tea还是the cup of tea 一杯美味的茶是a delicious cup of tea还是a cup of delicious tea? have a cup of tea,----?选择 have a cup of tea,will you? How about a cup of tea? please bring me a cup of tea. F____ me a cup of tea ,please . a cup of tea,怎么翻译,俗语.