问题补充:
Li ping’s brother is an boy.
A. eighteen-years-old
B. eighteen years old
C. eighteen-year-old
D. eighteen year old
答案:
A. eighteen-years-old
B. eighteen years old
(答案→)C. eighteen-year-old
D. eighteen year old
解析:此题重点考查合成形容词的基本构成;英语中几个单词之间用短横线连接起来,可以起一个类似于形容词的作用,注意每个单词都要用原形,因8的第一个音素是元音音素,故不定冠词用an.