摩擦性苔藓样疹的发病特点,以下哪项不正确()
A.多见于幼儿
B.常对称发疹
C.好发于手背及前臂
D.多见于夏季
E.由乙肝病毒引起
参考答案:E
-Listen! Helen is singing in the next room.
-It __________ be Helen. She has gone to Beijing.[ ]
A. can't
B. mustn't
C. may
D. should
什么是辐照技术?