The boy is playing chess with his grandfather.A. 8-years-oldB. 8 years oldC. 8-year-oldD.

问题补充：

The boy is playing chess with his grandfather.

A. 8-years-old

B. 8 years old

C. 8-year-old

D. 8 year old

答案：

A. 8-years-old

B. 8 years old

(答案→)C. 8-year-old

D. 8 year old

解析：句意：那个8岁的男孩正在和他的祖父下象棋。这里空格后有名词，所以这里需用的是复合形容词作定语。其结构是数词—名词的单数—形容词。8 years old不能作定语。故选C。