At present the students in China take more exercise. Most of them are than before. A. st

问题补充：

At present, the students in China take more exercise. Most of them are than before.

A. strong

B. stronger

C. strongest

D. the strongest

答案：

A. strong

(答案→)B. stronger

C. strongest

D. the strongest

解析：考查形容词比较级。句意“现在，中国的学生做更多的锻炼。大部分都比以前更强壮了。”than是比较级的标志，排除C、D；B是比较级，故选B。