问题 单项选择题

分布式数据库系统不具有的特点是

A.数据分布性和逻辑整体性

B.位置透明性和复制透明性

C.分布性

D.数据冗余

答案

参考答案:D

解析: 分布式数据库系统具有数据分布性、逻辑整体性、位置透明性和复制透明性的特点,其数据也是分布的;但分布式数据库系统中数据经常重复存储,数据也并非必须重复存储,主要视数据的分配模式而定。若分配模式是一对多,即一个片段分配到多个场地存放,则是冗余的数据库,否则是非冗余的数据库。

阅读理解

阅读理解。

      Modern life is impossible without traveling. The fastest way of traveling is by plane. With a modern

plane it takes one day to travel places which took a month or more to get to a hundred years ago.

     Traveling by train is slower than by plane, but it has its advantages(优势). You can see the country

you are traveling through. Modern trains have comfortable seats and dining-cars. They make even the

longest journey enjoyable.

     Some people prefer to travel by sea when possible. There are large planes and river boats. You can

visit many other countries and different parts of your country on them. Ships are not as fast as trains or

planes, but traveling by sea is a very pleasant way to spend a holiday.

     Many people like to travel by car. You can make your own timetable. You can travel three or four

hundred miles or only fifty or one hundred miles a day, just as you like. You can stop wherever you

wish --- where there is something interesting to see, at a good restaurant where you can enjoy a good

meal, or at a hotel where you can spend the night. That is why traveling by car is a popular pleasant trip,

while people usually take a train or a plane when they are traveling on business.

1. From the passage (短文), we know the fastest way of traveling is ____.

A. by train  

B. by sea

C. by plane    

D. by car

2. If we travel by car, we can _____.

A. make the longest journey enjoyable

B. travel to a very far place in several minutes

C. make our own timetable

D. travel only fifty or one hundred miles a day

3. The underlined (划线的) word "They" in the passage refers to (指的是)____.

A. modern trains in the country

B. comfortable seats and dining-cars

C. the travelers on the modern trains

D. the slower ways of traveling

4. When people travel on business, they usually take ____.

A. a plane or a car

B. a car or a boat

C. a boat or a train

D. a train or a plane

5. How many ways of traveling are mentioned (被提到的) in the passage?

A. Four.

B. Three.  

C. Two.  

D. Six

单项选择题