How about playing tennis中为什么play加ing

How about playing tennis中为什么play加ing playing tennis sounds interesting.中的play为什么加ing? 为什么Playing football.Play要加ing 为什么She likes playing tennis 中的 playing 带有ing?不加可以吗? look at the people playing basketball中为什么PLAY在加ing? I like playing volleyball为什么play要加ing? Lucy like playing sports 为什么play后加ing His hobby is playing football这里play为什么加ing l like playing sports .为什么play后面加ing? i like playing basketball 为什么play加ing how about playing tennis ? 改为同义句 play加ing成了playing是什么意思!