题目内容
实体-联系模型(简称E-R模型)中的基本语义单位是实体和联系。E-R模型的图形表示称为E-R图。联系可以同 (1) 实体有关。实体与实体之间的联系可以是 (2) 。利用E-R模型进行数据库的概念设计，可以分成三步：首先设计局部ER，然后把各个局部E-R模型综合成—个全局的模型，最后对全局E-R模型进行 (3) ，得到最终的E-R模型，E-R模型向关系模式的转换规则是把一个实体类型转换成一个关系模式，实体的属性是关系的属性，实体的键是关系的键。把一个联系类型转换成一个 (4) ，参与该联系类型的各实体的键及联系的属性转换成 (5) ，其中的键由实体与实体之间的联系决定。 4（）
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实体-联系模型(简称E-R模型)中的基本语义单位是实体和联系。E-R模型的图形表示称为E-R图。联系可以同 (1) 实体有关。实体与实体之间的联系可以是 (2) 。利用E-R模型进行数据库的概念设计，可以分成三步：首先设计局部ER，然后把各个局部E-R模型综合成—个全局的模型，最后对全局E-R模型进行 (3) ，得到最终的E-R模型，E-R模型向关系模式的转换规则是把一个实体类型转换成一个关系模式，实体的属性是关系的属性，实体的键是关系的键。把一个联系类型转换成一个 (4) ，参与该联系类型的各实体的键及联系的属性转换成 (5) ，其中的键由实体与实体之间的联系决定。 3（）
TASK 2Directions:This task is the same as Task 1．The 5 questions or unfinished statements arenumberedfrom 41 to 45. There are many ways to learn about people of other lands.One way is to study the clothing other people wear For thousands of years,people in different parts of the world have worn very different types of clothing.There are four big reasons for this． One reason might be religion.In many Moslem countries,women must wear veils to hide their faces.The veil must be worn in public.Veils are part ofthe Moslem religion． The second reason is that different materials are used in different countries.For instance,in France the materials used in clothing may be cotton(棉),silk,wool,or many other man-madematerials.Most people in China wear cotton． The way clothes are made are also very different.This is another reason why people dress differently.Western countries rely on machines to make most of their clothing.Someone living in India can use only hand power to make the clothing he needs． World-wide differences in customs also lead to differences in clothing.A Mexican farmer wears a straw hat with a brim up.In China,a farmer wears a straw hat with a brim down.Bothhats are used to protect the farmers from the sun.Some of these customs have come down through thousands of years. The third reason for the difference in clothing is______．
Directions:This section is to test your ability to understand short dialogues．There are fiverecorded dialogues in it.After each dialogue,there is a recorded question.Both the dialoguesand questions will be spoken twice.When you hear a question,you should decide on the correctanswer from the four choices marked A,B,C and D given in your test paper.Then you shouldmark the corresponding letter on the Answer Sheet with a single line through the center．
假定每一车次具有唯一的始发站和终点站。如果实体“列车时刻表”属性为车次、始发站、发车时间、终点站、到达时间，该实体的主键是 (1) ；如果实体“列车运行表”属性为车次、日期、发车时间、到达时间，该实体的主键是 (2) 。通常情况下，上述“列车时刻表”和“列车运行表”两实体间 (3) 联系。 3（）
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