何谓电涌保护器？
参考答案：
抑制传导来的线路过电压和过电流的装臵。与过电压保护器同类，也包括放电间隙、压敏电阻、二极管、滤波器等。
— I was told to be here at this time.
— Sorry, you ______. I forgot to tell you we've changed the plan. [ ]
A. must
B. may
C. can't
D. needn't
感染性心内膜炎栓塞症状有()
A．脾大
B．肝大
C．腹痛
D．胸痛
E．便血、血尿
