关系是通过两张表之间的______字段建立起来的。一般情况下,由于一张表的主关键字是

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问题:

关系是通过两张表之间的______字段建立起来的。一般情况下,由于一张表的主关键字是另一张表的______,因此形成了两张表之间的一对多的关系。

考点:计算机等级考试ACCESS数据库和表(二)
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阅读材料,回答所提问题

Linda loves her dog Davy. They went to New York City last Saturday. While Linda was buying a newspaper at the train station, the dog got out of his box and ran away. The station was crowded and Linda couldn’t see Davy anywhere. When Linda shouted his name, some people looked at her but Davy didn’t come. Then she called the police. While she was talking on the telephone, Davy met another dog outside the station. While the police were coming, Linda walked around the station and called Davy’s name. She didn’t think about looking outside the station. Finally, a little boy said to her, “Did you look outside? I saw a big black dog when I came in.” When Linda finally saw Davy, he was jumping and running with another dog. There was a police officer next to them. The police officer said to Linda, “I think my dog found your dog.”

小题1:What did Linda do when her dog ran away?

小题2:Why couldn’t Linda see Davy?

小题3:Where was Davy while Linda was looking for him?

小题4:What happened while Linda was on the telephone?

小题5:What was Davy doing when Linda finally saw him?

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期货市场在运作中由于管理法规和机制不健全等原因,可能产生()。

A.市场风险

B.交割风险

C.流动性风险

D.结算风险

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相似第一定理:若两个物理现象相似,则相似指标必为1;或者相似判据相等,且为常数。相似第一定理是相似的()。

A.必要条件 

B.充分条件 

C.相信判据存在定理

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河流袭夺现象是河流的下列哪种作用造成的?

A.侧蚀
B.下蚀
C.横向环流
D.机械侵蚀

题型:填空题

砂中含泥量试验(标准法)中,准确称取两份试样各400g,试验后干燥试样分别为393.5g,392.2g,求砂中含泥量。

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