下面不正确的说法是A．关键字是关系中能够用来唯一标识元组的属性 B．在一个关系中，关

发布时间：2017-05-25 12:55 │ 来源：www.tikuol.com

题型：单项选择题

问题：

下面不正确的说法是

A．关键字是关系中能够用来唯一标识元组的属性

B．在一个关系中，关键字的值不能为空

C．一个关系中的所有候选关键字均可以被指定为主关键字

D．关键字只能由单个的属性组成

考点：计算机等级考试数据库技术三级数据库技术笔试351

题型：单项选择题

阅读理解。

                                                    Letter 1
     Whatever I do, I always think about if other people will like it. How can I stop
worrying about what they think?
                                                                                          -Eva, 14, Illinois

                                                       Letter 2
      My dream is to be on the Olympic team for gymnastics. My dad thinks I started
too late and I'll never be able to make it. He puts me down, but I want his support.
What should I do?
                                                                                           -Erica, 9, Texas

                                              Letter 3
      What should I do if I failed a test? I'm afraid to tell my mom because she might
get mad at me and I can't play soccer. And soccer is like the world to me.
                                                                                      -Ashley, 12, Wisconsin

                                                   Letter 4
      I just moved and I'm kind of shy, so how do I make new friends?
                                                                                      -Jessica, 11, Canada

Dr. Molly's Answer ①
You should tell him about your dream and that if you work really hard, it might
happen even though you started late. The sooner you tell your dad how you feel, the
sooner you'll be able to work on making your dream come true.

Dr. Molly's Answer ②
Nobody knows you at your new school. You have nothing to lose, so gather up
all your courage and go over to someone who looks friendly and introduce yourself.
You can ask that person about your teacher or the other kids in your class to break
the ice. Good luck!

Dr. Molly's Answer ③
It's better to tell your mom the truth than for her to find out another way. When
you tell her, explain why you failed the test. Ask her if she can help you study in the
future, so you'll do better on your tests and also have time for the soccer you love.

Dr. Molly's Answer ④
Just be yourself and try not to care about what others think. The more you think
about it, the worse you will feel. Always act strong and confident. Even if you are a
little unsure of something, don't doubt (怀疑) your abilities to do things right. Just
relax.

1. Jessica ____________.

A. wonders how to make new friends
B. wishes to be on the Olympic team
C. is afraid to tell her mom about her failing a test
D. keeps worried about what other people think about her

2. ___________ loves playing soccer best.

A. Erica
B. Eva
C. Ashley
D. Jessica

3. Erica's dad doesn't support her because he thinks she ___________.

A. is a little shy and can't do it well
B. didn't start at a very early age
C. is too young to be on the team
D. doesn't work hard

4. According to Dr. Molly, Eva should ____________.

A. hold on to her dream
B. always tell the truth
C. be brave to say hello to others
D. be confident of herself

5. Which is the correct order of Dr. Molly's answers to the four letters?

A. ①④③②
B. ③④②①
C. ②③①④
D. ④①③②

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题型：单项选择题

书面表达。

假如Jim Green是你的朋友，请根据下面表格中提供的信息，把他介绍给你的加拿大朋友Jenny。

要求：包括表格中所有信息。另外，你可适当发挥。

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题型：单项选择题

读文答题。

　　……

　　“哥儿，有画儿的‘三哼经’，我给你买来了！”

　　我似乎遇着了一个霹雳，全体都震悚起来；赶紧去接过来，打开纸包，是四本小小的书，略略一翻，人面的兽，九头的蛇，……果然都在内。

　　这又使我发生新的敬意了，别人不肯做，或不能做的事，她却能够做成功。她确有伟大的神力。谋害隐鼠的怨恨，从此完全消灭了。

①当阿长买来《山海经》时，“我”有什么反应？

___________________________________________________________

②你怎样理解文中说的阿长“确有伟大的神力”？

___________________________________________________________

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题型：单项选择题

国家级重点文物保护的建筑物属于第（）类防雷建筑物？

A.1

B.2

C.3

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题型：单项选择题

社会主义法律适用的基本原则是（）

A、公民在法律面前一律平等

B、以事实为依据，以法律为准绳

C、国家赔偿与司法责任

D、执法必严，违法必究

E、报应原则

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