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The entity-relationship(E-R)data model is based on a perception of a real world that consists of a collection of basic objects,called（ ）,and of relationships among these objects.An entity is a“thing”or“object”in the real world that is distinguishable from other objects.Entities are described in a database by a set of（ ）.A relationship is an association among several entities.The set of all entities of the same type and the set of all relationships of the same type are termed an entity set and relationship set,respectively.The overall logical structure(schema)of a database can be expressed graphically by an E-R diagram,which is built up from the following components:（ ）represent entity set,（ ）represent attributes,etc.In addition to entities and relations,the E-R model represents certain（ ）to which the contents of a database must conform.The entity-relationship model is widely used in database design.
问题1选项
A.data
B.things
C.entities
D.objects
问题2选项
A.keys
B.attributes
C.records
D.rows
问题3选项
A.rectangles
B.ellipses
C.diamonds
D.lines
问题4选项
A.rectangles
B.ellipses
C.diamonds
D.lines
问题5选项
A.things
B.objects
C.conditions
D.constrains
Advancements in （ ）have contributed to the growth of the automotive industry through the creation and evolution of self-driving vehicles.
In project human resource management , （ ）is not a source of power for the project manager.
At the project establishment stage , the feasibility study mainly includes techinical feasibility analysis , （ ）, operation environment feasibility analysis and other aspects of feasibility analysis.
（ ）is a grid that shows the project resources assigned to each work package.
Xinhua News Agency reported in January 2022，Chian will further promote the developmet of a digital economy during the 14th Five-Year Plan eriod（2021-2025）. The plan also emphasized industrial （ ）transformation.
某公司投资一个使用寿命为5年的项目，第一年年初投入1000万元，从第1年到第5年每年年末都有净现金流量300万元。则项目的静态投资回收期为（ ）年。
下图是某地的街区网络图（单位:）里），疫情防控期间，一辆消毒车从疾控中心出发，需要消杀所有的街道并返回疾控中心。该消毒车完成消杀工作至少需要运行（ ）公里 。
某公司有东部、中部、西部三个生产基地，生产的产品需要运送带甲、乙、丙、丁四个市场，从生产基地到各个市场的单位运价及产量和需求量如表所示，完成该运输任务所需的最小运费为（ ）。
某炼油厂每季度需供应合同单位汽油15吨，煤油12吨，重油12吨，该厂从甲乙两处运回原油提炼，已知两处炼油成分如表所示，从甲处采购原油价格为2000元/吨，乙处为2900元/吨，为了使成本最低，炼油厂应从甲处购15吨，乙处采购（ ）吨。
某炼油厂每季度需供应合同单位汽油15吨，煤油12吨，重油12吨，该厂从甲乙两处运回原油提炼，已知两处炼油成分如表所示，从甲处采购原油价格为2000元/吨，乙处为2900元/吨，为了使成本最低，炼油厂应从甲处购（ ）吨，乙处采购20吨。
