The traditional model for systems development was that an IT department used (1) which is a process-centered technique, and consulted users only when their input or approval was needed. Compared with traditional methods, many companies find that JAD allows key users to participate effectively in the (2). When properly used, JAD can result in a more accurate statement of system requirements, a better understanding of common goals, and a per commitment to the success of the new system. RAD is a team-based techruque that speeds up information systems development and produces a functioning information system. While the end product of JAD is a(an) (3), the end product of RAD is the (4). The RAD model consists of four phases. During the (5), users interact with systems analysts and develop models and prototypes that represent all system processes, outputs, and inputs.

空白（4）处应选择（）

A.system proposal

B.system design model

C.new system architecture

D.new information system

一个关系相当于一张二维表，二维表中的各列相当于该关系的______。

A．数据项

B．元组

C．结构

D．属性