【判断题】这种不爱惜劳动成果、任意浪费,是可耻的。
【单选题】下列哪一项最可能导致生产可能性曲线向外移动()
【单选题】In the relational algebra θρ(r), ρ is called ( ).
【简答题】原材料和燃料费用的分配方法主要有 、 、 等。
【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
【简答题】The result of a relational-algebra
operation is ().A. relation B. tuple C. field D. keyword
【多选题】幼儿身体生长教育活动的总目标有
C.
帮助幼儿逐步树立关心、保护身体健康的意识和习惯
【单选题】Natural join is an additional operation in relational algebra, it can be replaced by which set of the following operations equivalently :
B.
Cartesian-Product, Project
C.
Cartesian-Product, Select, Project
D.
Cartesian-Product, Select