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问题 单项选择题

已知某市2014年人口数资料数据，如下表所示，则该市2014年的年平均人口数为（）万人。

A.515

B.520

C.526

D.535

答案

参考答案：C

解析：

这属于间隔不等的间断时点数列，故采用以间隔时间长度为权数的加权算术平均数来计算年平均人口数。已知：a=500.0，a=510.3，a=533.8，a=536.0，as=536.2；f=2，f=4，f=4，f=2。则=526（万人）

填空题

连通器的原理是：在连通器里装有同种液体，当液体______时，各容器中的______总保持相平．
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单项选择题

Networks can be interconnected by different devices. In the physical layer, networks can be connected by. (31) or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept (32) , examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have (33) network layer, the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message (34) . As an example, gateways between Internet E-mail and X. 400 e-mail must (35) the e-mail message and change various header fields.

（35）是（）

A.analyze

B.parse

C.delete

D.create
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