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【简答题】
对应于数据库关系模式R(A1,A2,A3)的一个关系中有三个,若对其进行任意的行位置和列位置交换操作(如行的排序等),则可以生成 个新的关系表。
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举一反三
【单选题】What does she look like? [ ]
A.
She is well.
B.
She is good.
C.
She is tall.
D.
She likes her.
【单选题】McGuire proposed Labor Day in order to ______.
A.
draw people's attention to the striking contrast between the rich and the poor
B.
make prominent the important role of the working class in society
C.
win for the workers the right to shorter working hours
D.
expose the exploitation of the workers by their bosses
【单选题】—What does your sister do ? — . [ ]
A.
She is in the supermarket.
B.
She is very tall.
C.
She is a teacher.
D.
She is fine.
【简答题】红外光导摄像管中,红外图像所产生的温度分布可以在靶面上感应出相应电压分布图像的物理基础是 ( )A. 光电效应 B. 电磁效应 C. 压电效应 D. 热电效应
【简答题】—What does your sister do ? — . A.She is in the supermarket. B,She is very tall. C.She is a teacher. D.She is fine.
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