当数据库出现故障时要对数据库进行恢复，恢复的原理是 (14) ，常用的技术是数据转储和 (15) 。
参考答案：[14]数据冗余
将下列问句的正确答语的序号填入题前括号里。
1. What do you see?[ ]
A. I see two tigers.
B. I can see two tigers.
2. What are the elephants doing?[ ]
A. It's drinking water.
B. They are drinking water.
3. Can you see the birds? [ ]
A. Yes, I can.
B. Yes, I see the birds.
4. What is the monkey doing?[ ]
A. They are swinging.
B. It's swinging.
清朝后宫中，六宫粉黛无颜色的六宫之首是什么身份？
