原发性三叉神经痛下列描述正确的是（）.
A.多见于青壮年
B.双侧受累多见
C.男性较多
D.可有痛性抽搐
E.多数患者可自愈
参考答案：D
— ____ he be at home now ?
— No . he ____ not . He ____ be in his office . He often goes home from work at almost twelve .
A．Can ; can ; must
B．Must ; need ; can
C．May ; must ; must
D．May ; need ; must
理想运算放大器工作在线性区时，具有虚断（）和虚短（）的特点。
