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案例分析题The UNIX operating system is made up of three parts; the kernel, the shell and the programs. The kernel of UNIX is the () of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to () .The shell acts as an () between the user and the kernel. When a user logs in, the () program checks the username and password, and then starts another program called the shell. The shell is a command line () (CLI). It interprets the commands the user types in and arranges for them to be carded out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems). The shell is a command line () (CLI).

A. interconnect
B. index
C. interface
D. interpreter

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案例分析题对长度为N的线性表进行查找,若采用顺序查找法,那么在最坏情况下所需要的比较次数为();若采用折半查找法,那么在最坏隋况下所需比较的次数为()。 若采用折半查找法,那么在最坏隋况下所需比较的次数为()。

A. [log2N]
B. [log2N]+1
C. [log2(N+1)]
D. [log2(N+1)]+1

案例分析题实体完整性约束指的是(),参照完整性约束指的是()。 参照完整性约束指的是()。

A. 若关系R的外码是属性(或属性组)F,它与关系S的主码K相对应,则关系S的主码K的取值必须在关系R中属性(或属性组)F的取值范围内
B. 若关系R的外码是属性(或属性组)F,它与关系S的主码,K相对应,则关系R中属性(或属性组)F的取值必须在关系S的主码K的取值范围内
C. 若关系R的外码是属性(或属性组)F,它与关系S的主码K相对应,则对于R中每个记录在F上的值必须等于S中某个记录的主码值。
D. 若关系R的外码是属性(或属性组)F,它与关系S的主码K相对应,则对于R中每个记录在P上的值或者取空值(F的每个属性值均为空值);或者等于S中某个记录的主码值。

案例分析题()是关系数据库的标准语言,它主要由()和一些其它语言要素组成。 它主要由()和一些其它语言要素组成。

A. 数据定义语言,数据操纵语言和数据控制语言
B. 数据定义语言,数据操纵语言和数据说明语言
C. 数据定义语言,数据说明语言和数据控制语言
D. 数据说明语言,数据操纵语言和数据控制语言

案例分析题The UNIX operating system is made up of three parts; the kernel, the shell and the programs. The kernel of UNIX is the () of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to () .The shell acts as an () between the user and the kernel. When a user logs in, the () program checks the username and password, and then starts another program called the shell. The shell is a command line () (CLI). It interprets the commands the user types in and arranges for them to be carded out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems). The kernel of UNIX is the () of the operating system.

A. hub
B. center
C. core
D. nucleus

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