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问题 填空题

设有关系R(A，B，C，D，E)，各属性函数依赖集合有FA→B，B→C,C→D，C→E若把关系R分解为R1(A，B，C) 和R2(C，D，E)则R2属于第 【18】 范式。

答案

参考答案：3NF

解析： 关系R的所有都不可再分，所以R∈1NF，则刚正1NF，R2∈1NF。 R2(C，D，E)的函数依赖集合为{C→D，C→E

单项选择题

（）是将商品集合总体按照一定的标志科学、系统地逐次划分为总类、大类、类别、组别、品目、及至规格、花色等细目的过程。

A.分类

B.商品分类

C.商品编码

D.物品分类
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单项选择题

Honesty comes in many forms. First there’s self honesty. Is what people see the real article or do you appear through smoke and mirrors I find that if I try to be something I’m not, I feel unsure of myself and take out a part from my PBA (personal bank account). I love how singer Judy Garland put it, "Always be a first class version of yourself, instead of a second class version of somebody else. "
Then there’s honesty in our actions. Are you honest at school, with your parents, and with your boss If you’ve ever been dishonest, I think we all have, try being honest, and notice how whole it makes you feel. Remember, you can’t do wrong and feel right. This story by Jeff is agood example of that:
In my second year of study, there were three kids in my math class who didn’t do well. I was really good at it. I would charge them three dollars for each test that I helped them pass. I’d write on a little piece of paper all the right answers, and hand them off.
At first I felt like I was making money, kind of a nice job. I wasn’t thinking about how it could hurt all of us. After a while I realized I shouldn’t do that any more, because I wasn’t really helping them! They weren’t learning anything, and it would only get harder down the road. Cheating certainly wasn’t helping me.
It takes courage to be honest when people all around you who are getting away with cheating on tests, lying to their parents, and stealing at work. But, remember, every act of honesty is a deposit into your PBA and will build strength.

The underlined part "appear through smoke and mirrors" in the first paragraph means ______.

A．to be honest
B．to be unreal
C．to become clear
D．to come from an imagined world
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