问题补充:
Millie is one of my best and she is a girl.
A. friends, friend
B. friend, friendly
C. friends, friendly
D. friendly, friend
答案:
A. friends, friend
B. friend, friendly
(答案→)C. friends, friendly
D. friendly, friend
解析:句意:米莉是我最好的朋友之一,她是一个很友好的女孩。one of +形容词最高级+名词的复数形式,表示“最…之一”,friendly友好的,故选C