管理罪犯监舍的警察原则上不少于居住在监舍罪犯总数的2%，实行24小时（）值班制。
参考答案：双人轮流
Whether you believe it or not, it was________ caused the serious accident.
A．because of your carelessness that
B．because you were careless
C．you were careless that
D．your being carelessness that
数据中心中某文件服务器遭受蠕虫病毒攻击，文件无法打开或已经损坏。这破坏了信息的（）
A、保密性和完整性
B、真实性和可用性
C、可用性和完整性
D、不可抵赖性和可用性
