硬膜外麻醉术中常见的并发症有（）
A.呼吸抑制
B.血压下降
C.心动徐缓
D.恶心呕吐
E.寒战反应
参考答案：A, B, C, D, E
251，222，193，( )
A．65
B．205
C．164
D．134
—_____ a year does your school have sports meetings?
—Twice a year. [ ]
A. How often
B. How soon
C. How long
D. How many times
