My sister's hobby is collecting stamps.为什么sister后面要加's,为什么co

My sister's hobby is collecting stamps.为什么sister后面要加's,为什么co Collecting stamps is my hobby 此句为何要用Collecting 为什么是is my My hobby is collecting stamps.为什么要用ing的形式啊? My hobby is collecting stamps. Collecting stamps is my hobby. My hobby is collecting stamps 【 】 stamp is my sister hobby a、collecting b、collects 说明为什么选This is my _____ dictionary.A sister's B sister,Mary's My hobby is Collecting Stamps 的作文 hobby,is,sister’s,what,your（要连词成句）后面是问号 是问句 It is my sister's birthday soon请讲解一下为什么要加It is 和soon的用法 my brother's sister is my(s ).