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如果关系模式R是2NF，且每个（）都不（）于R的（），则称R为3NF。（第1空4字,第2空6字，第3空3字）

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在关系模式R(U,F)中，U=ABCD，F=｛A→C，A→D｝，则R的候选码是（）,它最高可以达到（）NF。

在关系模式R(U,F)中，U=BCD，F=｛B→C，C→D｝，则R的候选码是(),它最高可以达到( )NF。

在关系数据库的规范化理论中，在执行分解时，必须遵守的规范化原则是（）和（）。（一空5字一空6字）

Listen to the passage and fill in the blanks with the words you hear. Scientists __1animals for many years. In 1952, the first animal, a tadpole, was cloned. Before the_2of Dolly, the first mammal cloned from the cell of an3, clones were created from embryonic cells. Since Dolly, researchers have cloned a number of large and small animals including sheep, goats, cows,_4, pigs, cats, rabbits, and a gaur. All these clones were created using __5.Hundreds of cloned animals exist today, but the number of 6_is limited. Attempts at cloning certain species have__7. Some species may be 8to somatic cell nuclear transfer than others. The process of stripping the nucleus from an_9_and replacing it with the nucleus of a donor cell is a traumatic one, and _10____may be needed before many species can be cloned successfully.