心室颤动立即用（）
A.注射利多卡因
B.静脉注射10％葡萄糖酸钙
C.同步直流电复律
D.非同步直流电复律
E.心音消失
参考答案：D
The Internet is an open system, and most information is available to everyone．It is very important to add ______ to existing system for protecting the secret information.
A．Web pages
B．modem
C．security
D．network
二层台
