我们成了最好的朋友 用英语在么说

we were the best of friends.

You are the best friend of mine
具体OF是
介词 prep.

1....的,属于
One of the legs of the table is broken.
桌子的一条腿坏了。
Mr. Brown is a friend of mine.
布朗先生是我的朋友。
学的多了后 就又中语感

we become best friends to each other.