My friend is nice改為雙重所有格 急解！！！?

A bad friend of mine is nice !!!

應改為
The friend of mine is nice.
但如果你把它寫成 A friend of mine is nice. 則意思會變為 我朋友之中只有一個人,人很好
因為a,the,和所有格不能連用,所以才要用到雙重所有格.

Reference :-My friend is nice.
(1)The nice friend is mine---------Possessive case
----He is mine.
(2)The nice friend belongs to me--------Objective case.
----He belongs to me.
-----The nice friend who is mine belongs to me.
(3)My friend (whom) you know is nice---------object form when "who" is the pronoun used as the subject.
--------That is my nice friend (whom) you know.
--------That is my nice friend (whom) you know about-----------the prep.placed at the end.
--------That is my nice friend( about whom) you know----------the prep placed before "whom".