Tony is a friend of my brother's.为什么有了of已经表示"的"了还要加'?能不能说Tony is a friend of my brother.

Tony is a friend of my brother's.为什么有了of已经表示的了还要加'?能不能说Tony is a friend of my brother. This litter is ( )my pen friend Tony My friend is Tony.改为一般疑问句 Tony is a menmber of the volleyball team.(改为同义词) Tony _____ _____ the volleyball team. Tony is a boy of 8.同义句 Last night,Tony and Vicky met a friend of ___ (they) in the market. a friend in word is never a friend of My new friend is Tony.(改为一般疑问句）回答：（ ）Tony ( ) new friend ...is a friend of +名词?名词所有格? Tom is a best friend of mine. He is a friend of mine.翻译. Mary is a friend of ____(I). What is a Friend of the Earth? mr li is a friend of _ he is a friend of mine A friend of ( ) [he] is from Japan what is your definition of a friend he is a friend of _____(we)