Although there are no classes in the afternoon now, no student go out of school without the head teacher’s permission.
A. will
B. must
C. may
D. shall
网友回答
A. will
B. must
C. may
(答案→)D. shall
解析：考查情态动词用法。当shall用于第二第三人称时，表示命令，警告，允诺，威胁，法律，规范。根据the teacher's permission可知。