He isn't at school. He ______________ be ill. [ ]
A. may
B. should
C. must
D. need
答案:A
下列哪项不是月经后期血虚型的主症()
A.经期延后,量少,色淡红
B.头晕眼花,心悸少寐
C.面色苍白或萎黄
D.舌质红,少苔,脉细数
E.小腹空痛
变压器过负荷时应如何消除?