请问,为什么是a friend of hers 而不是a friend of her?

请问,为什么是a friend of hers 而不是a friend of her? a friend of her还是a friend of hers 为什么是a friend of mine 而不是a friend of me 呢 Judy is a friend of (选择） A me B her C she D hers 为什么是lucy is a friend of li lei而不是lucy is a friend of li lei′ Betty met a friend of (she,her ,hers)in the street. A friend of hers came to see you last night. 请问这是什么从句?While traveling in English,she met a friend of hers 关于名词所有格比如:是BANK OF CHINA 而不是BANK OF CHINA's,为什么?是a friend of an old friend of hers hers能开头吗 比如hers an old friend对吗 为什么 Friend of a Friend 歌词 Helen is a friend of___.A.hers B.her