问题 填空题

为了实现数据库管理系统的三组模式之间的联系,数据库管理系统提供了两个映像,它们是外模式/模式映像和【 】。

答案

参考答案:模式/内模式映像

解析:为了实现数据库三级模式之间的联系和转换,数据库管理系统在这三级模式 之间提供了两层映像:外模式/模式映像和模式/内模式映像。这两层映像保证了数据库 系统的数据独立性。

单项选择题
单项选择题

(B)

When I was six, Dad brought home a dog one day, who was called "Brownie". My brothers and I all loved Brownie and did different things writh her. One of us would walk her, another would feed her, then there were baths, playing catch and many other games, Brownie, in return, loved each and every one of us. One thing that most touched my heart was that she would go to whoever was sick and just be with them, we always felt better when she was around.

One day, as I was getting her food, she chewed up one of Dad’s shoes, which had to be thrown away in the end. I knew Dad would be mad and I had to let her know what she did was wrong. When I looked at her and said, "Bad girl," she looked down at the ground and then went and hide. I saw a tear in her eyes.

Brownie turned out to be more than just our family pet, she went everywhere with us. People would stop and ask if they could pet her. Of course she’d let anyone pet her. She was just the most lovable dog. There were many times when we’d be out walking and a small child would come over and pull on her hair. She never barked or tried to get away. Funny thing is she would smile. This frightened people because they thought she was showing her teeth. Far from the truth, she loved everyone.

Now many years have passed since Brownie died of old age. I still miss days when she was with us.

Why does the author say that Brownie was more than just a family pet()

A. She was treated as a member of the family.

B. She played games with anyone she liked.

C. She was loved by everybody she met.

D. She went everywhere with the family.