对于关系R，第二范式是要求R中的每一个非主属性满足______。A．

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问题单项选择题

对于关系R，第二范式是要求R中的每一个非主属性满足______。

A．没有重复的组项

B．只有简单的重复项

C．完全函数依赖于主关键字

D．单值依赖关系

答案

参考答案：C

单项选择题

将研究对象按照个人为单位用掷硬币的方法(正、反面分别代表实验组和对照组)随机分配到实验组和对照组。此种分组方法为

A．简单随机分组

B．分层随机分组

C．整群随机分组

D．系统随机分组

E．未进行随机化分组

单项选择题

The reason that this story was made known to the public was the fact that ______.

A．USA TODAY requested Freedom of Information Act to act on its behalf

B．Freedom of Information Act requested USA TODAY to act on its behalf

C．USA TODAY managed to obtain copies of the documents that contained the contract

D．Freedom of Information Act so stated that USA TODAY was able to obtain the documents