请问这句英语句子对吗?My favorite sports is playing football.为什么?

请问这句英语句子对吗?My favorite sports is playing football.为什么? My favorite outside class activities is playing football. 英语 My favorite sportes is football.有语法错误吗?为什么这里要用sports复数形式? playing football is my favourite s------.是sports?用加s吗,为什么? My favorite sport is playing table tennis .请问；为什么要用playing? 请问这句英语是什么意思my computer is playing up The boy playing football yesterday is my son 这个句子对吗 Phelps is my favorite sports star,改成同义句 There are some boys playing football.这句子里面为什么用playing?能否分析下句 The boy who likes playing football is my son.这个句子为什么不能改成ing做 Playing the guitar is my favorite.(同义句） Football is my favorite sport.的同义句