学生表中有"学号"、"姓名"和"年龄"三个字段,SQL语句"SELECT 学号 FROM 学生"完成的关系操作称为(  

学生表中有"学号"、"姓名"和"年龄"三个字段,SQL语句"SELECT 学号 FROM 学生"完成的关系操作称为(  )。 A.选择 B.投影 C.连接 D.

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请在第__(48)__处填上正确答案。

请在第__(48)__处填上正确答案。A.If you are feeling down, you normally don't sit straight, w

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There are various forms of adult education, including_______

There are various forms of adult education, including__________.A.by social and

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The policeman wrote down all the particulars of the accident

The policeman wrote down all the particulars of the accident.A.secrets B.details

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The study suggests that it is more difficult to respond what

The study suggests that it is more difficult to respond what to get rid of.A.Rig

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