It is required that the students mobile phones in our school so seldom them using one.

问题补充：

It is required that the students mobile phones in our school, so seldom them using one.

A. can’t use; will you see

B. not use; will you see

C. mustn’t use; will you see

D. shouldn’t use; you will see

答案：

A. can’t use; will you see

(答案→)B. not use; will you see

C. mustn’t use; will you see

D. shouldn’t use; you will see

解析： 考查虚拟语气和倒装。It是形式主语，that the students mobile phones in our school是主语从句，require后面的主语从句要用(should)+do的虚拟语气，所以排除A,C；seldom表否定意义，用于句首时，后面句子部分倒装，所以选B。