题目详情

本题作答（_问题1_）： In systems analysis and design, a Data Flow Diagram (DFD) is a structured analysis tool used to represent how data flows through a system and how processes transform data. The DFD is created during the early stages of system development to provide a （ 问题1） understanding of the system’s functionality. A DFD consists of four basic components: processes, data stores, data flows, and external entities. These components are used to model the system’s （ 问题2） rather than its physical implementation. The （ 问题3） represent the transformations of data from input to output, each typically named using a verb-noun phrase. Data flows represent the movement of data between components.（ 问题4） are repositories where data is stored for future use.External entities represent actors outside the system that interact with it, such as users or external systems. DFDs are typically developed in a top-down manner, beginning with a context diagram (or level 0 diagram), which shows the entire system as a single process and its interaction with external entities. This is followed by a （ 问题5）, which breaks down the main process into sub-processes for greater detail.