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【单选题】
已知关系 R 和 S ,则 R ∩ S 等价于 ( )A.
(R-S) ∩ S
B.
R ∩ (R-S)
C.
S-(R-S)
D.
R-(R-S)
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【简答题】B The African grey parrot’s ability to talk and mimic sounds makes it a charming companion. African grey owners often report that their greys oftentimes talk in context and can understand their people...
【简答题】下列各项中，不属于工程建设项目评标方法的是（ ）。
【单选题】下列各项中不属于工程建设项目管理服务需求目标的是______
A.
工程建设项目功能、标准、规模
B.
保证工程建设项目按照合同约定条件、设计图纸与技术标准、方案组织实施
C.
投资与效益、进度、质量
D.
职业健康/安全、环境
【简答题】Text 2 Biologists estimate that as many as 2 million lesser prairie chickens---a kind of bird living on stretching grasslands—once lent red to the often gray landscape of the midwestern and southweste...
【单选题】Jenny, ________the tree! Can you ________ the red bird in the tree?
A.
watch; look
B.
look; see
C.
see; watch
D.
look at; see
【单选题】The bird is singing _____________ the tree. The red apples are _____________ the tree. [ ]
A.
in, on
B.
on, in
C.
at, on
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