怎样区别在什么时候别the 什么时候不加the 例如.playing the piano or playing football.

乐器前加the 运动前不加the

带器械的加the，如：play the piano/violin，不带器械的不加the，如：play football, play basketball, 等等。

the是修饰名词的,用法有 1.第二次提到某物 This is a book.The book is mine.2.谈话双方所知道的事物Open the window ,please.3.世界上独一无二的事物the sun,the moon,the earth 4.方向The sun rises in the east.5...