a friend of Jack还是 a friend of Jack's

a friend of Jack还是 a friend of Jack's Mr Black is a friend of ______.A.Jack's aunt B.Jack aunt's C Jack is a friend of ___ A.my B.my brother C.my brother's D.m Here's a friend of a friend of Here's a friend of a friend o tony said jack was a good friend of （） A.he.B.h a friend of sb's jack and mark are friend of ( ) A him B his C he D hes a friend of my还是a friend of mine a friend of her还是a friend of hers a friend of I还是a friend of me a friend of Tom表达对,还是a friend of Tom's对 a friend of Tom,还是 a friend of Tom's 或者两个都对?