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问题 单项选择题 案例分析题

对传输线路导线材料及截面积的技术要求。

应采用铜芯绝缘导线或铜芯电缆，其电压等级不应低于（）。

A.直流250V

B.交流250V

C.直流220V

D.交流220V

答案

参考答案：B

单项选择题

An internet is a combination of networks connected by (1).When a datagram goes from a source to a(2)，it will probably pass many (3)until it reaches the router attached to the destination network. A router receives a (4)from a network and passes it to another network. A router is usually attached to several networks. When it receives a packet, to which network should it pass the packet? The decision is based on optimization: Which of the available (5)is the optimum pathway?

空白（2）处应选择（）

A.user

B.host

C.city

D.destination
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多项选择题

概算定额是由（）组成的。

A.总说明

B.项目表

C.定额附录

D.工程量计算规则
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