Jane is high school student in the United States.A. a 18-year-oldB. a 18-years-oldC. an 18

问题补充：

Jane is high school student in the United States.

A. a 18-year-old

B. a 18-years-old

C. an 18-year-old

D. 18-years-old

答案：

A. a 18-year-old

B. a 18-years-old

(答案→)C. an 18-year-old

D. 18-years-old

解析：句意：简是美国的一名18岁的高中学生。年龄作定语的形式为：数字-year-old,因为18是元音音素开头的故用不定冠词an来修饰，故选C。