什么时候用PLAYING

什么时候用PLAYING 什么时候用plays什么时候用playing 什么时候用play什么时候用playing 什么时候用play什么时候用plays什么时候用playing 什么时候用play,什么时候用playing例句：Listen!The boy is ___(play) the piano in the music room.___处为什么要填playing 英语 什么时候加s语法除复数外,都是什么时候加s啊?什么时候用likes什么时候用like?like后动词必须加ing?比如 like playing? play football 什么时候play是playing,什么时候是plays,句子 请问什么时候用is什么时候用are?比如A..B的句式我就不知道后面是随A还是随B、?就是有比如小花as long as两个男孩是are playing还是is playing 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. 英语什么时候要在动词后面加s/es?还有,什么后面要用动词原形?什么时候用s,什么时候用es?比如：Does she plays chess?Do you plays chess?Do you playing chess? playing playing 动名词和不定动词!Playing computer games too much is bad for your eyes.这句话为什么要用Playing而不用To play动名词和不定动词的区别是什么?什么时候该用哪个? as well as连接动词 用法He publishes as well as prints his own books.She sings as well as playing the piano请说明两个句子的区别.什么时候用动名词?什么时候用动词原形? 英语基本语法问题Mobile phones are playing a great part in my daily life .和Mobile phones playa great part in my daily life .谁是正确的?什么时候应该用are 什么时候不用? Tom kikes playing football 用playing football提问 he is playing football用playing football提问 Playing sports is good for us 这里为什么用playing