1.形容词性代词所有格.my ,your,his ,its ,their后必须跟名词.
注意its 与it's的区别,前者是"它的"所有格,后者是"它是."的缩写
2.名词性代词所有格是重点和难点:名词性所有格后不需跟名词.
Your book is red,Mine is black.(=My book is black.)
It's not my letter.It's yours.(=it's your lrtter)
He hid his cake in the frige,he is eating hers.(=he is eating her cake)
She is not our teacher.She is theirs.=their teacher
Your classroom is beautiful,Ours is more beautiful.
My father is a doctor,while his（=his father） is a teacher.(只有his 和its的形容词所有格和名词所有格是相同的.)
The cat looked at the tiger,the tiger's legs are long,while its（=its legs） are short.
mine,yours,hers,ours,theirs,his,its相当于一个上文已出现过的名词:如我的书,你的信,她的蛋糕,他的父亲,他们的老师,它的腿.