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

9个月小儿，身高80cm，体重 15kg，每天户外活动2～3小时，近日出现多汗、烦躁、夜惊。查体：枕秃，轻度肋缘外翻。该患儿患佝偻病的可能原因是

A．未补钙

B．未加辅食

C．生长过速

D．未补充鱼肝油

E．患有某些疾病