Rail，like many project managers,had studied the waterfall model of software development as the primary（主要） software life-cyle process.(Rail，像很多项目经理一样，学过瀑布模型，它是一个重要的软件生命周期过程)He has all set to use it for an upcoming project,his first assignment（分配）.(他准备用瀑布模型来搭建他第一个分配到的项目)However,Ravi found that the waterfall model could not be used because the customer wanted the soft delivered in stages,something that implied that the system had to be delivered and build in parts and not as a whole.(尽管如此，Rail发现不能用瀑布模型因为客户希望软件按阶段来交付，这暗示着这个系统要被交付并且是分部分的而不是一个整体)
The situation in many other projects is not very different.(这个情况在其他项目也差不多)The real world rarely presents a problem in which a standard process,or the process used in a previous project,is the best choice.（这个当前真实的世界，也很少有一种标准的过程或者在前期的项目中使用的过程作为当前项目最好的选择）To be the most suitable,an existing process must be tailored（裁剪） to the new problem.（作为最合适，面对新的问题，存在的过程应该进行裁剪）
A development process,even after tailoring,generally cannot handle change requests.（一个开发的过程，在裁剪之后，通常不能控制改变的需求）To accommodate change requests without losing control of the project,you must supplement（补充） the development process with a requirement change management process.（为了适应改变的需求而不失去控制，你必须用需求变更管理过程来补充这个开发过程）