The network layer provides services to the transport layer．It call be based on either virtual circuits or datagrams．In both cases，its main job is（　　）packets from the source to the destination．

A． dealing with

B． sending

C． routing

D． receiving

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参考答案

网络层为传输层提供服务，它基于虚电路或数据报方式，其主要工作是对源节点的数据包进行路由选择(routing)，转发到目的节点。

1 （　　）iS a property of object—oriented software by which an abstract operation ma)’be performed in different ways in different classes．

A． Method

B． Polymorphism

C． Inheritance

D． Encapsulation

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2 The（　　）process ascertains which risks have the potential of affecting the project and documenting the risks’characteristics．

A． Risk Identification

B． Quantitative Risk Analysis

C． Qualitative Risk Analysis

D． Risk Monitoring and Control

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3 The（　　）provides the project manager with the authority to apply organizational resources to project activities。

A． project management plan

B． project charter

C． project human resource plan

D． project stakeholders

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