皮皮学，免费搜题
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搜题
【单选题】
表扬是对学生思想和行为的( )。
A.
认可、鼓励和支持
B.
默认、赞同
C.
一种心理暗示
拍照语音搜题，微信中搜索"皮皮学"使用
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参考解析：
知识点：
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皮皮学刷刷变学霸
举一反三
【判断题】这种不爱惜劳动成果、任意浪费,是可耻的。
A.
正确
B.
错误
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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
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
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【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
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【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
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【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
相关题目：
【判断题】这种不爱惜劳动成果、任意浪费,是可耻的。
A.
正确
B.
错误
查看完整题目与答案
【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