软件方法学是以软件方法为研究对象的学科。软件工程是一门指导计算机软件(36)维护的工程学科。描述软件开发过程中各种活动如何执行的模型来看，有瀑布模型，增量模型，螺旋模型，喷泉模型，基于知识的模型，变换模型等。其中传统的生命周期方法可用(37)来模拟。应用传统的生命周期方法开发软件的过程中，首先进行软件定义，其中需求分析阶段用到的工具有(38)。软件开发中测试是非常重要的一环。测试的目的是(39)。软件开发交付用户使用之后就要进行软件维护，软件维护的方法有四种：校正性维护、适应性维护、(40)。

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In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

 To a router, a flow is a(71)of packets that share the same characterstics, such as traveling the same(72), using the same(73), having the same kind of security, and so on. A router that supports the handling of flow labels has a(74)table. The table has an entry for each Active flow label; each entry defines the(75)required by the corresponding flow label.

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In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

 In low - speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high - speed networks, this approach often works poorly, because in the(66)between sending the notification and notification arriving at the source, thousands of additional(67)may arrive. In ATM network, a major tool for preventing(68)is(69)control. When a host wants a new virtual(70), it must describe the traffic to be offered and the service expected.