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建筑工程职业资格公务员财会类医卫类外语类计算机类学历类

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In a world where

it seems we already have too much to do, and too many things to think about, it

seems the last thing we need is something new that we have to learn.

But use cases do

solve a problem with requirements:with （71） declarative requirements it's hard to describe steps and sequences of

events.

Use cases, stated

simply, allow description of sequences of events that, taken together, lead to

a system doing something useful.As simple as this sounds,this is important.

When confronted only with a pile of requiements, it's often（72）to make sense of what the authors of the

requirements really wanted the system to do.In the preceding example, use cases

reduce the ambiguity of the requirements by specifying exactly when and under

what conditions certain behavior occurs;as such, the sequence of the behaviors can

be regarded as a requirement. Use cases are particularly well suited to capture

approaches. Although this may sound simple, the fact is that （73） requirement capture approaches, with their

emphasis on declarative requirements and "shall"

statements,completely fail to capture fail to capture the （74） of the system's behavior. Use cases are a

simple yet powerful way to express the behavior of the system in way that all

stakeholders can easily understand.

But,like

anything, use cases come with their own problems, and as useful as they

are,they can be （75）. The result is something that is as bad, if not worse, that the original

problem.Therein it's important to utilize use cases effectively without

creating a greater problem than the one you started with.

A.statics
B.nature
C.dynamics
D.originals

正确答案及解析

正确答案

解析

在这个世界上，似乎我们有太多的事情要去做，有太多的事情要去思考，那么需要做的最后一件事就是必须学习新事物。而用例恰恰可以解决带有需求的问题：如果具有严格声明的需求，则很难描述事件的步骤和序列。简单地说，用例可以将事件序列的说明放在一起，引导系统完成有用的任务。正如听起来一样简单---这很重要。在面对很多需求的时候，通常不太可能理解需求的作者真正想要系统做什么。在前面的例子中，通过指定特定行为发生的时间和条件，用例减少了需求的不确定性。这样的话，行为的顺序就可以当作是一种需求。用例特别适用于捕捉这类需求。尽管听起来可能很简单，但事实情况是由于常规的需求捕捉方法所侧重的是声明需求和“应该怎么样”的陈述，因此完全无法捕捉系统行为的动态方面。用例是一种简单而有效的表达系统行为的方式，使用这种方式所有参与者都很容易理解。

但是与任何事物一样，用例也存在自己的问题---在用例非常有用的同时，人们也可能误用它，结果就产生了比原来更为糟糕的问题。因此重点在于：如何有效地使用用例，而又不会产生比原来更严重的问题