为什么Jack hurt his back playing volleyball中的play用的是ing形式而不是过去式

为什么Jack hurt his back playing volleyball中的play用的是ing形式而不是过去式 Jack hurt his hand ( )play volleyball.用to play还playing答案是pla Jack hurt his back playing volleyball.为什么用palying?什么语法? I like playing volleyball为什么play要加ing? started playing a sport 为什么用过去式和ing 形式 hurt的过去式和ing形式 He likes playing basketball.为什么这里的play用的是ing形式,这应该不是正在进行时吧? My favorite sport is playing basketball 中的play后面为什么要加ing形式 My favorite sport is playing……中的play后面为什么要加ing形式 His hobby is playing football这里play为什么加ing Let+us+playing+soccer.+为什么play要用ing形式? He stopped playing soccer because of his sore back.为什么用过去式