【单选题】【消耗次数：1】
关系代数运算是以( )为基础的运算。
①
关系运算
②
谓词演算
③
集合运算
④
代数运算
参考答案：
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相关题目
【单选题】
算术运算符、赋值运算符和关系运算符的运算优先级按从高到低依次为（）。
①
算术运算、赋值运算、关系运算
②
算术运算、关系运算、赋值运算
③
关系运算、赋值运算、算术运算
④
关系运算、算术运算、赋值运算
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Following are comments about the behavior that people in Korea usually expect in various social _____.
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occasions
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cases
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situations
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circumstances
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The elbows on your coat have worn thin, so I must _____them.
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mend
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patch
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repair
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Mac’s close _____to his brother made people mistake them for one another.
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resemblance
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identity
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The thieves _____the waste paper all over the room while they were searching for the diamond ring.
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spread
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scattered
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George was introduced to _____activities at a young age, when she was hired to act as a lookout for drug-dealers.
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illegal
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treatment
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When I read the newspaper, I always read the _____ first.
①
headlines
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headquarters
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The millions of circulations involved, _____ by hand, would have lost all practical value by the time they were finished.
①
had they been done
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they had been done
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having been done
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they were done
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Betty advised me to label our luggage carefully in case it gets _____ in transit.
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misused
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mishandled
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mislaid