下列哪几项不是内伤头痛的特点（）
A.痛势绵绵
B.时痛时止
C.长久不愈
D.其痛如破
E.突然而作
参考答案：D, E
The old man is badly ill and he needs ___________ to hospital at once.
A．to be taken
B．to take
C．be taken
D．taken
解释重掺杂半导体使禁带变窄的原因。
