问题 填空题

1NF消除______依赖,即规范化为2NF;2NF消除依赖非主属性对码的传递函数,即规范化为3NF。

答案

参考答案:非主属性对码的部分函数

解析: 在讨论关系模式向2NF、3NF转化的问题时,都是只涉及非主属性对码的依赖关系,前者是消除部分函数依赖,后者是消除传递函数依赖。

阅读理解

阅读理解。

     The high school years are a key period. The things we learn during this time really shape our lives. Liu

Changming, principal of Beijing No. 4 High School made 18 suggestions for students just starting high school

on how to get the best out of high school. Here are ten of them.

1) Read 50 books. But choose them from ten different fields.

2) Help a person. Look for a classmate, an elderly person, in fact anyone who could benefit (获益) from your

    help. You'll find you benefit too!

3) Research. Research a particular area, such as science, history or art.

4) Make a foreign friend. Try to befriend someone from a foreign country. It's an ideal way to learn about a

    foreign country.

5) Publish (出版) an article. Whether it appears in a newspaper, your school magazine or in your own blog,

     an article will be something to look back on in pride in later years.

6) Take up a new sport. Choose one you've never played before. If you find you like it, you'll have a hobby

    for life.

7) Join a club. Working hard in a club or other activities will give you a life outside of your studies.

8) Find a part-time job. Try and do the job for at least a month.

9) Find a person to learn from. Choose someone with unusual experience or special talent. Try to learn all

    you can from him or her.

10) Learn to cook four Chinese dishes. Learning how to cook is not only a practical skill but a way of

      building a  bridge to other people.

1. According to the passage, by making a foreign friend you can ________. 

A. learn about another culture

B. practice spoken English

C. discuss the international situation

D. share your happiness and sadness

2. Beside learning a practical skill, another purpose of learning to cook is ________. 

A. to help your parents with housework

B. to kill time

C. to have communication with others

D. to make friends

3. Which of the following statements is True according to the passage?

A. You should read fifty books of the same field.

B. Do a part-time job for less than a month.

C. Try to publish an article to make you famous.

D. You can benefit a lot by helping others.

4. The principal made the suggestions in order for the students to ________. 

A. make contributions to society

B. achieve greet progress in high school

C. love high school life

D. finish high school

名词解释