计算机类 - 计算机四级

单选题

Ⅰ．网络性能<br>Ⅱ．系统可靠性<br>Ⅲ ．网络体系结构<br>Ⅳ ．通信费用

A. Ⅰ和Ⅱ
B. Ⅰ、Ⅱ和Ⅲ
C. Ⅰ、Ⅱ和Ⅳ
D. 全部

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单选题

ATM是一种面向连接的快速分组交换技术，它采用虚拟通道模式，通道标识基于的标识符是

A. (N)PDU和(N)IDU
B. VPI和VCI
CONNECT．reguest和CONNECT．indication
D. (N)SAP和(N+1)SAP

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单选题

Which of the following statements is true regarding simple sort techniques？

A. Exchange sort is frequently referred to as a bubble sort.
B. Exchange sort is the least expensive.
C. If random data are in an array that is to be sorted, an Insertion Sort will give the best performance for large elements with small sort items.
D. Both Insertion Sort and Selection Sort require O(n)moves.

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单选题

在OSI参考模型中，两个(N)成实体之间交换的数据单元称之为(N)协议数据单元，记做(N)PDU。(N)PDU由两部分组成：(N)PCI与

A. (N+1)IDU
B. (N+1)SDU
C. (N)SDU
D. (N)IDU

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单选题

网络文件访问是网络系统的基本功能，TCP/IP、XNS与SNA均有网络文件访问协议。网络文件访问包括两种不同的形式：文件传输与文件访问。文件访问又叫做访问 (on-lineaccess)，它

A. 要求用户直接将远地文件全部拷贝到本地文件系统
B. 允许多个远地程序同时访问单个文件，在原文件上进行操作，而没有文件拷贝过程
C. 要求本地用户连入局域网中
D. 要求用户通过电子邮件方式交换信息

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单选题

下面推理中<br>正确的是

A. a、b和c都正确
B. c和d正确
C. a和b正确
D. 只有a正确

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单选题

用数组A[0,N-1]存放循环队列的元素值，若其头指针和尾指针分别为front和rear，则循环队列中当前元素的个数为

A. (rear-front+N+1)mod N
B. (rear-front+1)mod N
C. (rear-front-1+N)mod N
D. (rear-front)mod N

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单选题

What is the definition of a Path？

A sequence of vertices and the edges formed by each successive pair of vertices.
B. A walk with distinct vertices.
C. A walk with distinct edges.
D. None of the above

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单选题

Which function is NOT served by building a prototype？

A. It takes the place of the final system.
B. It assists in gathering software requirements
C. It assists in estimating the cost of the project.
D. It is used as the foundation of the larger projects.

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单选题