Mary is primary school student in Beijing.A. a 8-year-oldB. an 8-year-oldC. a 8-years-ol

问题补充：

Mary is primary school student in Beijing.

A. a 8-year-old

B. an 8-year-old

C. a 8-years-old

D. an 8-years-old

答案：

A. a 8-year-old

B. an 8-year-old

C. a 8-years-old

D. an 8-years-old

解析：

试题分析: 句意：玛丽是北京的一名小学生。 8-year-old 8岁，做复合形容词，其中的名词保持单数，eight的第一个音标为元音，加不定冠词an,故答案选B.