数据库系统由数据库、（1）和硬件等组成，数据库系统是在（2）的基础上发展起来的。数据库系统由于能够减少数据冗余，提高数据独立性，并集中检查（3），十几年来获得了广泛的应用。

3（）

A．数据完整性

B．数据层次性

C．数据操作性

D．数据兼容性

词汇运用

1. A cultural relic is something _________(留存很长的)．

2. You can buy whatever you want with the ________(剩下的)money.

3. Put the chain back ________(它该在的地方)．

4. The beautiful necklace is ________(妈妈给我的礼物)．

5. Although it feels as hard as stone,it easily melts ________(遇热时)．

6. She took ________(点燃的蜡烛) into the dark room and immediately the room ________(亮起来了)．

7. He says he can do it,but I am rather ________ (怀疑的) about it.

8. ________(考虑到) his age,he did very well in the exam.

9. At last,their theory ________(证明是正确的)．

10. She pretended ________(别人已告知此事)．