The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modern software development. The notions of (21) and scenarios have been proven to be an excellent way to capture function requirements. RUP can be described in two dimensions - time and content. In the time dimension, the software lifecycle is broken into cycles. Each cycle is divided into four consecutive (22) which is concluded with a well-defined (23) and can be further broken down into (24) - a complete development loop resulting in a release of an executable product, a subset of the final product under development, which grows incrementally to become the final system. The content structure refers to the disciplines, which group (25) logically by nature.

A．functions

B．workflows

C．actions

D．activities

回归分析的任务就是对指标变量之间是否存在必然的联系、联系的形式、变动的方向做出符合实际的判断，并测定它们联系的密切程度，检验其有效性。（）