）My new friend is a boy.
A. fifteen-year old
B. fifteen-years-old
C. fifteen years old
D. fifteen-year-old
网友回答
A. fifteen-year old
B. fifteen-years-old
C. fifteen years old
(答案→)D. fifteen-year-old
解析：英语中两个或多个单词中间可以用短横线连接起来，起一个相当于形容词的作用，这类单词叫做合成词。其一般构成规则就是其构成单词一般都要用原形。句意:我的新朋友是个十五岁的男孩。结合语境可知选D。