DBMS是位于__(1)__之间的一层数据管理软件。关系数据库的概念模式是__(2)

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问题:

DBMS是位于__(1)__之间的一层数据管理软件。关系数据库的概念模式是__(2)__的集合,外模式是__(3)__的集合。用符号(+)表示的关系操作称为__(4)__操作。

空白(3)处应选择()

A.二维表

B.基本表

C.视图

D.文件

考点:中级数据库系统工程师关系数据库基本理论关系数据库基本理论题库
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某房东外出时忘记锁门,结果小偷进屋,家具被偷,则风险因素是()。

A.小偷进屋

B.家具被偷

C.外出时忘记锁门

D.房东外出

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尽管我们关于太阳能的研究和议论已经相当多,但今天对太阳能的利用还是非常有限的,其主要原因是( )。

A.尚未开发出有效的收集和储存太阳能的系统

B.核能仍然有效

C.太阳能系统尚不安全

D.难以将阳光有效地聚集

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阅读理解。

     Some people think that as more and more people have televisions in their homes, fewer and fewer people

will buy books and newspapers. Why read an article in the newspaper, when the TV news can bring you the

information in a few minutes and with pictures? Why read the life story of a famous man, when a short

television program can tell you all that you want to know?

     Television has not killed reading, however. Today, newspapers sell in very large numbers. And books of

every kind are sold more than ever before. Books are still a cheap way to get information and enjoyment.

Although some books with hard covers are expensive, many books are printed today as paperbooks (平装本),

which are quite cheap. A paperback collection of short stories, for example, is always cheaper than an evening

at the cinema or the theater, and you can keep a book for ever and read it many times.

     Books are a wonderful provider of knowledge and pleasure and some types of books should be in every

home. Every home should have a good dictionary. A good encyclopedia (百科全书), though expensive, is

useful, too, because you can find information on any subject. Besides, you can have such books as history

books, science textbook, cookbooks, and collections of stories and poems. Then from time to time you can

take a book of poems off your shelves and read the thoughts and feelings of your favorite poets.

1. It can be inferred from the passage that _____.

A. TV programs are a chief provider of knowledge

B. cinemas are the best choice in getting information

C. reading is a cheap way of learning and having fun

D. newspapers are an expensive way to enjoy oneself

2. What does the sentences "Television has not killed reading, however" underlined in the second paragraph

    suggest?

A. People only need reading, though.

B. Reading is still necessary today.

C. Reading is more fun than television.

D. Watching television doesn't help reading.

3. Which of the following is mainly discussed in the last paragraph?

A. Types of books.

B. Kinds of dictionaries.

C. Lists of history books.

D. Collections of stories and poems.

4. What can we learn from the passage?

A. Fewer and fewer people will buy books.

B. A good dictionary should be kept in every home.

C. Books with hard covers sell better than paperbooks.

D. More people like TV programs about famous men.

题型:单项选择题 共用题干题

骨盆轴是指()

A.连接骨盆各平面任选点而成的假想轴线

B.连接骨盆各平面横径中点而成的假想轴线

C.连接骨盆各平面中点而成的假想轴线

D.连接骨盆各平面前后径中点而成的假想轴线

E.以上都不是

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当进口最终产品的名义关税税率高于所用的进口原材料的名义关税税率时,有效关税保护率( )

A.大于最终产品的名义关税税率
B.等于最终产品的名义关税税率
C.小于最终产品的名义关税税率
D.小于零

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