Oneofthesuspectsis

问题详情：

 One of the suspects is _________ boy.

A. a 18-year-old                                                   B. an 18-years-old

C. a 18 years old                                                  D. an 18-year-old

【回答】

D   18-year-old作定语，其中的year用单数形式。

知识点：构词法

题型：选择题