Issues involved in this problem area include: 1. Achieving requirements completeness without unnecessarily constraining the system design 2. Analysis and validation difficulty 3 Changing requirements over time.

• 在需求的问题上有这样一些观点:1、到达需求的完整性会束缚系统设计。2、需求分析和验证比较困难3、改变需求会消耗额外的时间。