But the traditional descriptive procedure by the natural language is inaccurate because of the lack of describe formalization and result in the comprehension deviation.

• 然而，以往用自然语言描述系统需求的方法，缺乏描述的形式化，随意性较人，往往引起理解上的含混和不准确性，并最终造成需求遗漏甚或产生偏差。