The girl talking to Mary is a friend of (Mary's sister's).括号内的能否用(Mary sister's)和（sister of Mary's)「是语法问题么?说明一下理由,要完整!」
问题描述：
The girl talking to Mary is a friend of (Mary's sister's).括号内的能否用(Mary sister's)和（sister of Mary's)「是语法问题么?说明一下理由,要完整!」
答
前一个语法错误