在关系代数运算中，(23)运算结果的关系模式与原关系模式相同。

A query is used to search through the database to locate a particular record or records, which conform. to specified (75) .

A Web (73) is one of many software applications that function as the interface between a user and the Internet

Files can be lost or destroyed accidentally．Keep (74) copies of all data on removable storage media．

The (72) is a collection of modules serving as interface between hardware and software to provide a software platform．

Each program module is compiled separately and the resulting (71) files are linked together to make an executable application.

(55)

(53)

CPU中，保存当前正在执行的指令的寄存器是(59)。表征指令执行结果的寄存器是(60)。

(51)

软件测试通常采用黑盒测试和白盒测试。其中黑盒测试根据软件的(55)设计测试用例，白盒测试根据软件的(56)设计测试用例。