问题 单项选择题

用树形结构来表示实体之间联系的模型称为( )。

A.关系模型

B.层次模型

C.网状模型

D.数据模型

答案

参考答案:B

解析: 目前常用的数据模型有3种:层次模型、网状模型和关系模型。在层次模型中,实体之间的联系是用树结构来表示的。

阅读理解

阅读理解。

     Most middle school students wear uniforms. Some students like uniforms, but others don't. However,

recently, a Japanese government survey (政府调查) shows that more students in Japan like uniforms

now because school uniforms are more fashionable (时尚的) than they were before.

     I surveyed some Japanese students about what they thought about school uniforms. I asked them,

"Do you like fashionable uniforms?" There were lots of different opinions (观点, 看法).

     Hiromi said, "I like school uniforms because I don't need to choose clothes every day. I think that

fashionable uniforms are good. My high school uniform is fashionable, but there is a problem. Fashionable uniforms are too expensive."

     Miki said that she didn't like fashionable uniforms because she didn't want to spend too much money

on uniforms. She thought that the uniforms should be changed(被改变). They should be cheaper and

easier to get.

     Mitsuaki said, "I don't like school uniforms because I want to look different. I also agree that

fashionable uniforms make many students want to wear uniforms in high school. If students like

fashionable uniforms, it is good. "

1. Do more students or fewer students like uniforms in Japan now?

    _____________________________________________________________________

2. What is the question of the survey?

    _____________________________________________________________________

3. How many students' opinions are there in the passage?

    _____________________________________________________________________

4. Why does Hiromi like school uniforms?

    _____________________________________________________________________

5. Why do students not like school uniforms?

    _____________________________________________________________________

单项选择题