Lucy is a girl.A. 12 years oldB. 12-years-oldC. 12 year oldD. 12-year-old

问题补充：

Lucy is a girl.

A. 12 years old

B. 12-years-old

C. 12 year old

D. 12-year-old

答案：

A. 12 years old

B. 12-years-old

C. 12 year old

(答案→)D. 12-year-old

解析：句意：露西是一个十二岁的女孩。几个英文单词中间由短横线链接可以表达一个整体的含义，其中每个单词一般都要用原形，故本题选D，意思是十二岁的。