数据流图是常用的进行软件需求分析的图形工具，其基本图形符号是

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问题单项选择题

A．输入、输出、外部实体和加工

B．变换、加工、数据流和存储

C．加工、数据流、数据存储和外部实体

D．变换、数据存储、加工和数据流

答案

参考答案：C

选择题

家燕是善于飞行的鸟类，身上最发达的肌肉是（　　）

A．翅膀上的肌肉

B．腿部的肌肉

C．躯干部的肌肉

D．胸部的肌肉

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单项选择题

Traditional IP packet forwarding analyzes the____(1)____IP address contained in the network layer header of each packet as the packet travels from its source to its final destination．A router analyzes the destination IP address independently at each hop in the network．Dynamic ____(2)____protocols or static configuration builds the database needed to analyze the destination IP address(the routing table)．The process of implementing traditional IP routing also is called hop—by—hop destination—based____(3)____routing．Although successful，and obviously widely deployed，certain restrictions，which have been realized for some time，exist for this method of packet forwarding that diminish its____(4)____．New techniques are therefore required to address and expand the functionality of an IP—based network infrastructure．This first chapter concentrate on identifying these restrictions and presents a rew，architecture，known as multipIeprotocol____(5)____switching，that provides solutions to some of these restrictions．

(3)

A．anycast

B．multicast

C．broadcast

D．unicast

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