问题 单项选择题

在关系数据库中,若数据库的存储结构改变了,而用户的应用程序可以不变这是( )。

A.数据的物理独立性

B.数据的逻辑独立性

C.数据的位置独立性

D.数据的语义独立性

答案

参考答案:A

解析:当数据库的存储结构改变了,由数据库管理员对模式/内模式映像做相应改变,可以使模式保持不变,从而应用程序也不必改变。保证了数据与应用程序的物理独立性,简称数据的物理独立性。

阅读理解

I was sitting in the room reading when I heard a loud noise. To defend my home from break-in, I picked up my defense weapon--- a broom and went out. There on the roof of my porch(门廊), I saw a grey fluffy squirrel. I drove her away with the broom, but the next day I heard her again.

I searched squirrels on the net and found because their teeth keep growing, they have to constantly chew on things to shorten their teeth. This was disturbing so I asked my husband to call in some wildlife control people.

On Monday morning two men showed up, with guns in their hands. I pointed uneasily to the hole in my porch roof. They held up their guns. Suddenly I saw in my mind the baby nursery inside. I stopped them and confirmed that they wouldn’t harm her. They hesitated, but finally put down their guns. Then they brought out a bottle of deodorizer(除臭剂)and sprayed it into the squirrel’s home. They told me she would not like the smell and would leave.

There was no sign of Mrs. Squirrel, so they blocked the hole, took my cheque for $250 and left. Shortly after they left, Mrs. Squirrel returned from her shopping trip. She was mad at being driven out and began feverishly clawing at the porch roof. In order to stop the destruction of my home, I drove her away with the broom again.

Each day thereafter, Mrs. Squirrel continued her attack on my possession. I then called the company to report that “SHE’S BAAAAAACK…” The receptionist said that if Mrs. Squirrel had managed to find another way into my porch roof, it would be a new charge. I replied I couldn’t continue contributing my husband’s hard-earned income to their silly wildlife experts and hang up.

I went to the porch and banged on the roof. Mrs. Squirrel came out and glared at me. We negotiated some terms, came to an agreeable arrangement and went back into our respective homes.

All is quiet these days, although large quantities of materials have been removed from my garage wall and my daughter claims that some of her doll-house furniture has disappeared. I still hope that Mrs. Squirrel would leave, but I will wait until it is warmer and hopefully until after the birth of the little ones.

小题1:What did the author think of the squirrel at first?

A.Troublesome.

B.Dangerous.

C.Interesting.

D.Clever.小题2:Why didn’t the author ask the wildlife control people to come again?

A.She worried about the safety of the squirrel.

B.She thought the company charged too much.

C.She decided to drive away the squirrel herself.

D.She doubted the ability of the wildlife control people.小题3:What can we learn from the passage?

A.Getting rid of the squirrel needs patience.

B.The squirrel has destroyed the author’s house.

C.The author has developed affection for the squirrel.

D.The author singed an agreement with Mrs. Squirrel.小题4:The author has written the passage in a (an) ________ way.

A.persuasive

B.serious

C.informative

D.amusing

填空题