There are about more than five left-behind students (留守学生) in China.A. millionB. millions

问题补充：

There are about more than five left-behind students (留守学生) in China.

A. million

B. millions

C. million of

D. millions of

答案：

(答案→)A. million

B. millions

C. million of

D. millions of

解析：句意：在中国有超过五百万的留守学生。确定的所指时，million不加of,不加s.故选A.