闸门埋件上的不锈钢座板，宽为100㎜，也和埋件一样进行防腐施工。
参考答案：错
下列哪一项是数据库系统的核心和基础
A．数据模型
B．数据库管理系统
C．数据库技术
D．关系理论
用名词所有格填空。
1. ________ (Jeff and Mary) schools are very different.
2. My ________ (father)glasses are on the dresser.
3. ________ (Mr. Johnson) house is very small.
4. Those are the ________ (children) books.
5. That________ (girl) clothes are very smart.
6________ (Bill) house is new.
7. The________ (teachers)cars are yellow.
