题目内容
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。
查看答案
搜索结果不匹配？点我反馈
更多问题
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 ______1______animals for many years. In 1952, the first animal, a tadpole, was cloned. Before the_______2______of Dolly, the first mammal cloned from the cell of an______3______, 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 ________8______to 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.
Listen to the following passage and fill in the missing words. One beautiful spring morning I was alone in my room, reading. Suddenly a 1.__________smell in the air made me get up and put out my hands. The 2.__________ of spring seemed to be3. __________in my room. “ What is it?” I asked. The next minute I knew it was coming from a mimosa tree outside. I walked outside to the4.____________ of the garden, toward the tree. There it was, 5._________ inthe warm sunshine. Its long branches, so heavy with flowers, almost touched the ground. I walked through the flowers to the tree itself and then just stood 6.___________. Then I put my foot on the tree and 7.__________myself up into it. I climbed higher and higher until I reached a little 8. __________. Long ago someone had put it there. I sat for a long time ... Nothing in all the world was like this.
.在Unity中，每新建一个工程都会自动产生四个文件夹，其中哪个文件夹包含该工程中的所有设置（ ）
微信支付 
支付宝支付