问题 单项选择题

在关系数据库中,表(table)是三级模式结构中的( )。

A.外模式

B.模式

C.存储模式

D.内模式

答案

参考答案:B

解析:三级模式是对数据的3个抽象级别,从外向内依次为外模式、模式和内模式。外模式又称为子模式或用户模式,它是数据库用户看见和使用的局部数据的逻辑结构和特征的描述,是与某一应用有关的数据的逻辑表示,是数据库用户的数据视图。模式又称逻辑模式,是数据库全体数据的逻辑结构和特征的描述,不涉及数据物理存储,是数据库管理人员视图。内模式又称为存储模式,它描述数据的物理结构和存储结构,它是系统程序员视图。

阅读理解

阅读理解。

 

     Eating out is more popular in Britain today than it has ever been. It is reported that British people spend

 more eating out than cooking for themselves and eating at home. It seems that many British people are

 becoming more and more interested in how good their food tastes, and also how healthy it is.

     However, eating out can also be expensive, so British people do not eat out  every night. When having 

 a date with friends, or having a birthday, many people like to go to a restaurant, and people also eat in a

  restaurant before going to the cinema or the theater.

     As in all cultures, there are many rules of manners about eating. The knife and fork should be used in

 the correct way. It is also impolite to speak with your mouth full when you are eating.

     Most British cities have a large collection of food as well as British food, from the very cheap to the

 very expensive: French, Italian, Indian, Chinese, Thai, Japanese and many, many more.

     When people are too tired to cook after work, they often get a "takeaway". This means that they order

 from a take-out restaurant by telephone, and then go to get it. Many take-out restaurants also send it to

 your house. All you have to do is to open the door, pay and eat!

1. When do British people often eat in a restaurant?

    A. After having a birthday.              

    B. Before watching a movie.

    C. When they feel tired.              

    D. If they want to have natural food.

2. Many people prefer to eat out nowadays because _____.

    A. eating out is cheaper than cooking at home

    B. they can learn more manners in the restaurant

    C.people care more about their food than before

    D. people don't like to stay at home after work

3. From the fourth paragraph, we can learn that _____.

    A. British dishes are very expensive

    B. Japanese dishes are most expensive

    C. British people like foreign food

    D. French food is most popular

4. The "takeaway" is the food _____.

    A. you order and take out of the restaurant

    B. that is left when you are eating in a restaurant

    C. you order but don't need to pay at once

    D. that is sold and ordered only on the phone

5. What is the best title (标题) of the passage?

    A. British restaurant culture.                    

    B. British table manners.

    C. Best restaurants in Britain.                    

    D. Best food in Britain.

填空题