1)a large number of men always around a girl who is my friend.
4)a girl was always arounded by a group of men ,the girl who is my friend
正确,意思是一群男人老是围着一个女孩,那女孩是我朋友.
5)my brother always arounds a girl who is my friend
8)a girl was always arounded by my brother,the girl who is my friend
正确,我哥哥老是围着一个女孩,那女孩是我朋友.
2)a large number of men always around a girl,the girl who is my friend.
6)my brother always arounds a girl,the girl who is my friend
错误,不应该加the girl 因为先行词a girl
跟从句时紧挨的
7)a girl was always arounded by my brother who is my friend
3)a girl was always arounded by a group of men who is my friend
错误,这种情况应该加the girl
否则它就指代的是my brother ,a group of men
定语从句的构成 先行词（名词）+ 引导词（关系代词 关系副词） + 定语从句
用结构分析,自己体味,语感也很重要的.