One of the rules is that every student wear school uniform while at school.
A. might
B. could
C. will
D. shall
网友回答
A. might
B. could
C. will
(答案→)D. shall
解析：考察情态动词用法。Shall表示允诺，强制，命令；（或者法律规定要做的事情）；本题考察的正是法律规定中要做的事情。结合句意可知D正确。句意：其中有一个规则说：学生在校期间，每个学生都要校服。