ZPW-2000A型无绝缘移频自动闭塞发送器采用（）冗余。
A.双机热备
B.双机冷备
C.N+1
D.N+2
参考答案：C
用适当的阿拉伯数字填空。
1. There are ___________ months in a year.
2. There are ___________ weeks in a month.
3. There are ___________ days in a week.
4. There are ___________ days in a year.
5. There are ___________ hours in a day.
数据库设计的根本目标是要解决
A．数据共享问题
B．数据安全问题
C．大量数据存储问题
D．简化数据维护
