单项选择题硬盘上的数据读写速度与______有关。
单项选择题运算器、控制器和内存储器的总称是______。
单项选择题比较字符大小实际是比较它们的ASCⅡ码值,以下正确的比较是______。
单项选择题OMT定义了三种模型来描述系统。(36)可以用状态图来表示;(37)可以用数据流图来表示。(38)为上述两种模型提供了基本的框架。
单项选择题若关系诊疗科和医师进行自然连接运算,其结果集为(10)元关系。医师和患者之间的治疗观察关系模式的主键是(11)。
单项选择题UML是一种面向对象的统一建模语言。它包含10种图,其中,用例图展示了外部 actor与系统所提供的用例之间的连接,UML中的外部actor是指(51),用例可以用(52)图来描述。状态图指明了对象所有可能的状态及状态间的迁移(Transition)。如果一个并发的状态由n个并发的子状态图组成,那么,该并发状态在某时刻的状态由(53)个子状态图中各取一个状态组合而成。协作图描述了协作的(54)之间的交互和链接(link),它画成(55)图的形式。
单项选择题请找出下列程序中错误之处 ______。#include<iostream.h>class A{private:int x1;protected:int x2;public:int x3;};class B:public A{private:int y1;protected:int y2;public:int y3;void disp(){cout<<x1<<y1<<end1:} Avoid set(int i) {x2=i;} B};void main() {B bb;bb.x3=10; Cbb.y3=10; D}
单项选择题宽带广域网络可采用(54)技术实现,其骨干网应选用(55)作为主要通信介质,节点之间的连接不宜采用(56)结构。
单项选择题下列问题是基于以下叙述:有关系模式R(A,B,C,D) ,F={(A,D) →C,C→B}。R的所有候选码为______。,(A,C)
单项选择题Microsoft's COM is a software architecture that allows applications to be built from binary software components. COM is the underlying(71)that forms the foundation for higher-level software services, like those provided by OLE. COM defines a binary standard for function calling between components, a way for components to dynamically discover the interfaces implemented by other components, and a mechanism to identify components and their interfaces uniquely.OLE is a compound(72)standard developed by Microsoft. OLE makes it possible to create(73)with one application and link or embed them in a second application. Embedded objects retain their original format and(74)to the application that created them. Support for OLE is built into the Windows and MacOS Operating Systems. A(75)compound document standard developed mainly by Apple and IBM is called OpenDoc.