操作系统通常将I/O软件分成4个层次：用户应用层软件、中断处理程序、独立于设备的软件和设备驱动程序，分层的主要目的是(25)。

(79)

(77)

(78)

(76)

The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modern software development. The notions of use-cases and (71) 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 (72) which is concluded with a well-defined (73) and can be further broken down into (74) - 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 (75) logically by nature.

(72)

(74)

设关系模式R＜U,F＞，其中U{H,I,J,K,L}，若F={H→IJ,J→K,IJK→L,L→H,L→K)，则F的最小函数依赖集Fmin={(54)}，关系模式R的候选关键字是(55)。

设有职工实体Employee(职工号，姓名，性别，年龄，通信地址，家庭成员)，其中通信地址记录了邮编、省、市和街道信息；家庭成员记录了职工亲属的姓名。

 职工实体中的通信地址是一个(51)属性；为了将数据库模式设计的更合理，对于家庭成员属性(52)。

(70)