My friend Vivian is an girl.
A. seventeen- year- old
B. seventeen years old
C. eighteen –year –old
D. eighteen years old
网友回答
A. seventeen- year- old
B. seventeen years old
(答案→)C. eighteen –year –old
D. eighteen years old
解析：C 考查数词加名词作定语。a/ an+数词-year-old +名词，表示“一个……岁的人”。“一个18岁的女孩”an eighteen–year–old girl，eighteen首字母发音是元音，故用冠词an。