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【多选题】
国家空间数据基础设施的内容包括（）。
A.
数据
B.
标准
C.
技术
D.
政策
E.
组织
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【单选题】下列哪一项最可能导致生产可能性曲线向外移动（）
A.
消费品生产增加，资本品生产减少
B.
有用性资源增加或技术进步
C.
通货膨胀
D.
失业
查看完整题目与答案
【单选题】下列哪项最不可能由低钙导致
A.
婴儿手足搐搦症
B.
惊厥
C.
佝偻病
D.
婴幼儿枕秃
E.
甲状腺功能亢进
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【单选题】In the relational algebra θρ(r), ρ is called ( ).
A.
select operation
B.
rename
C.
project predicate
D.
selection predicate
查看完整题目与答案
【单选题】下列哪项最可能导致DNA变性( )
A.
加入巯基乙醇
B.
加入甲酰胺及尿素
C.
搅拌
D.
磷酸二酯键的断裂
E.
丙酮
查看完整题目与答案
【单选题】The symbol ρ is a ( ) operator in relational algebra.
A.
intersect
B.
select
C.
rename
D.
project
查看完整题目与答案
【单选题】Divisionis an additional operation in relational algebra, it can be replaced by which set of the following operations equivalently?
A.
Select, Project , Cartesian-Product
B.
Union, Project, Cartesian-Product
C.
Select, Rename, Cartesian-Product
D.
Set difference, Project, Cartesian-Product
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【简答题】The result of a relational-algebra operation is ().A. relation B. tuple C. field D. keyword
查看完整题目与答案
【判断题】The operator ( ) associates every tuple of two tables in relational algebra.A. ∏ B. × C. θ D. ρ
A.
正确
B.
错误
查看完整题目与答案
【单选题】Natural join is an additional operation in relational algebra, it can be replaced by which set of the following operations equivalently :
A.
Select, Project
B.
Cartesian-Product, Project
C.
Cartesian-Product, Select, Project
D.
Cartesian-Product, Select
查看完整题目与答案
【简答题】根据不同分类标准简述采购与供应的分类
查看完整题目与答案
相关题目：
【单选题】下列哪一项最可能导致生产可能性曲线向外移动（）
A.
消费品生产增加，资本品生产减少
B.
有用性资源增加或技术进步
C.
通货膨胀
D.
失业
查看完整题目与答案
【单选题】下列哪项最不可能由低钙导致
A.
婴儿手足搐搦症
B.
惊厥
C.
佝偻病
D.
婴幼儿枕秃
E.
甲状腺功能亢进
查看完整题目与答案
【单选题】In the relational algebra θρ(r), ρ is called ( ).
A.
select operation
B.
rename
C.
project predicate
D.
selection predicate
查看完整题目与答案
【单选题】下列哪项最可能导致DNA变性( )
A.
加入巯基乙醇
B.
加入甲酰胺及尿素
C.
搅拌
D.
磷酸二酯键的断裂
E.
丙酮
查看完整题目与答案
【单选题】The symbol ρ is a ( ) operator in relational algebra.
A.
intersect
B.
select
C.
rename
D.
project
查看完整题目与答案
【单选题】Divisionis an additional operation in relational algebra, it can be replaced by which set of the following operations equivalently?
A.
Select, Project , Cartesian-Product
B.
Union, Project, Cartesian-Product
C.
Select, Rename, Cartesian-Product
D.
Set difference, Project, Cartesian-Product
查看完整题目与答案
【简答题】The result of a relational-algebra operation is ().A. relation B. tuple C. field D. keyword
查看完整题目与答案
【判断题】The operator ( ) associates every tuple of two tables in relational algebra.A. ∏ B. × C. θ D. ρ
A.
正确
B.
错误
查看完整题目与答案
【单选题】Natural join is an additional operation in relational algebra, it can be replaced by which set of the following operations equivalently :
A.
Select, Project
B.
Cartesian-Product, Project
C.
Cartesian-Product, Select, Project
D.
Cartesian-Product, Select
查看完整题目与答案
【简答题】根据不同分类标准简述采购与供应的分类
查看完整题目与答案