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．artifacts

B．use-cases

C．actors

D．workers

关于经线和纬线的正确叙述是：                                                     

A．所有经线的长度皆相等；

B．所有经线都与本初子午线平行；

C．所有的经线圈和纬线圈都能平分地球；

D．45⁰纬线的长度是0⁰纬线的一半