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问题 填空题

在关系运算中，______运算是在给定关系的某些域上进行的运算。

答案

参考答案：投影

解析： 在关系运算中，投影运算是在给定关系的某些域上进行的运算。

阅读理解

Victoria Middle School Report         Student: Jenny Brown
Math
B
good work all year
Chinese:
A
does well this year
English:
A+
very interested in it and does a very good job
Science:
C
A little weak in this subject
Computer:
D
not really interested and needs to improve
Sports:
A
captain of girls’ soccer team, and also on the basketball team
Total Grade
B
 
Date:1/4/10       Signed: Ms Ding
小题1:Whose school report is it?
A．Victoria’sB．Ms Yang’s
C．Jenny Brown’sD．We don’t know
小题2:Which subject of the following was Jenny best at?
A．MathB．ChineseC．ScienceD．English.
小题3:How did Jenny do in sports?
A．WellB．So-soC．Very badly.D．Badly.
小题4:From the report, we can know that Jenny       .
A．is good at computer
B．does well in Chinese
C．like science better than math
D．is the captain of the basketball team
小题5:Which of the following is TRUE?
A．Jenny is very interested in English.
B．Jenny is the best student in her class.
C．Jenny doesn’t do well in math at all.
D．Jenny does well in all the subjects.
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填空题
把二次根式3 
1
3
中根号外的因数移到根号内，结果是______．
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