继发性低颅压性头痛最常见原因是（）。
A.脑室分流术后
B.硬膜或腰椎穿刺后
C.头颈部外伤后CSF外漏
D.低血压
E.脑膜脑炎
参考答案：B
—Look at the sign on the right.
—Oh, parking ______ here.
A．doesn’t allow
B．isn’t allowed
C．didn’t allowed
D．wasn’t allowed
They________him to be chairman of the Students' Union.[ ]
A．appreciated
B．approached
C．approved
D．appointed
