全国计算机等级考试四级笔试试题范文.docx

全国计算机等级考试四级笔试试题一、选择题。(共90题,分为1分题和2分题,满分120分。除标注2分题外,其它均为1分题。） (1) 若或非门的输入变量为A和B,输出变量为Y,则A和B分别为下述哪一种情况时, Y才为1?_。 A) 1,0 B) 0,1 C) 0,0 D) 1,1 (2) 已知寄存器A存有带符号整数且只作算术移位,HA和LA分别代表其最高位和最低位。寄存器B存有带符号整数且只作逻辑移位,HB和LB分别代表其最高位和最低位。当寄存器A与B都有左移位发生时,下述哪一个命题是正确的? _。(2分) A) LA与LB均成为0 B) LA与LB均成为1 C) LA变成0但LB保持原值 D) LA保持原值但LB的值改变 (3) 下述哪一种情况称为指令周期? A) 取指令时间 B) 取操作数时间 C) 取指令和执行指令的时间 D) 存储操作结果的时间 （4）2010年网络中交易额最大的电子商城网站是下面哪个A）见效美白站B）114购物网C）淘宝网D）淘宝网男装 (5) 设Z是整数集,且设f:ZZZ,对每一个ZZ,有f()=mn。集合0的原象为_。(2分) A) 0Z B) Z0 C) (0Z)(Z0) D) (0Z)(Z0) (6) 对于一个只有3个不同元素的集合A来说,A上的等价关系的总数为 _。 A) 2 B) 5 C) 9 D) 取决于元素是否为数值 (7) 设有命题:对于组成元素为集合的集合C,存在函数为f:CC,使得对每一个 SC,有f(S)S。 该命题的否命题是_。 A) 对于集合C,对每个函数f:CC,对每一个SC,都有f(S) S B) 对于集合C,存在函数f:CC,使对每一个SC,有f(S) S C) 对于集合C,对每一个函数f:CC,存在SC,使得f(S) S D) 对于集合C,不存在函数f:CC,使对某些SC,没有f(S) S (8) 设(V,E)是一连通的无圈图,V包含 3个3度顶点 2个2度顶点 r个1度顶点 且V不再包含其他元素。E的元素个数为多少?_。 (2分) A) 6 B) 9 C) 15-r D) 5+5r (9) 设连通图G的顶点数与边数与一立方体相同,即有8个顶点和12条边。任意一棵G的生成树的总边数为_。 A) 7 B) 8 C) 9 D) 10 (10) 设图G的顶点为五边形P的顶点,其边为P的边加上另一条连接P的两个不相邻顶点的边。下列命题中哪个(或哪些)命题是真命题? . G中存在欧拉回路 . G中存在哈密尔顿回路 A) 均不是 B) 只有 C) 只有 D) 和第11-13题是在已知下述Pascal程序的基础上,并设在程序执行过程中无错误发生。 for h:=1 to n-1 do begin x:=Ah+1; k:=h; while (k=1) and (Akx) do begin Ak+1:=Ak; k:=k-1 end; Ak+1:=x end; (11) 假设在程序开始执行时,数组A1.n是一个已排好序的递增序列。下列答案中,哪一个最好地描述了程序的执行时间(运行时间阶数)? _。 A) O(log2n) B) O(n) C) O(nlog2n) D) O(n) (12) 假设在程序开始执行时,数组A1.n是一组随机整数。下列答案中,哪一个最好地描述了最差情况下的程序执行时间(运行时间阶数)? _。 A) O(log2n) B) O(n) C) O(nlog2n) D) O(n) (13) 上述程序算法的标准名称是_。 A) 起泡排序法 B) 插入排序法 C) 选择排序法 D) 快速排序法 (14) 下面关于B树和B+树的叙述中,不正确的结论是_。 A) B树和B+树都是平衡的多分树 B) B树和B+树都可用于文件的索引结构 C) B树和B+树都能有效地支持顺序检索 D) B树和B+树都能有效地支持随机检索 第(15)-(16)题基于下面的叙述:某二叉树结点的对称序序列为A,B,C,D,E,F,G,后序序列为B,D,C,A,F,G,E。 (15) 该二叉树结点的前序序列为_。 (2分) A) E,G,F,A,C,D,B B) E,A,C,B,D,G,F C) E,A,G,C,F,B,D D) E,G,A,C,D,F,B (16) 该二叉树对应的树林包括多少棵树?_。 (2分) A) 1 B) 2 C) 3 D) 4 第(17)-(18)题是有关DOS操作系统的内容: (17) 设驱动器为D,下述哪一个命令可以用来分页显示根目录下的文件清单_。A) DIR D: B) DIR D: C) DIR /P D: D) DIR /P D: (18) 若将DOS的提示符改成MS-DOS5FILE1 SORTFILE2 DEL FILE1 DATE TIME IF EXIST %1 ECHO % IF FOUND If all of the commands are successfully executed after IF1 FILE1 is typed, then the screen displays?_ A) None B) Date and time C) FILE1 IS FOUND D) FILE2 IS FOUND (70) If the files in the current directory are aac, abc, acb,acc, aca, ao, al, a2, ab, ac, aa, and the command ls a?bc is executed, how many files will be listed?_ (2分) A) 3 B) 4 C) 5 D) 6 B) (71) In order to append a standard output to an existing file, which of the following operators is used in the UNIX system? _ A) | B) & C) D) (72) Consider the following figure, where the shaded parts represent already assigned blocks of memory, and the unshaded parts represent free blocks. (2分) If there is a request for 40KB of memory and the best-fit algorithm is used, then the beginning address of memory that is allocated in response to the request is _. A) 100KB B) 190KB C) 330KB D) 410KB (73) On a certain disk, there are 200 tracks, numbered 0-199, the current position of the disk head is track 53. If the shortest-seek-time-first scheduling algorithm is used when the tracks 98, 183, 37, 122, 14, 124, 65, 67 are requested, then the head-moving sequence that results will be (2分) A) 65, 67, 37, 14, 98, 122, 124, 183 B) 65, 67, 37, 98, 122, 124, 183, 14 C) 65, 67, 98, 122, 124, 183, 37, 14 D) 98, 183, 37, 122, 14, 124, 65, 67 (74) Whant operation on relations R and S produces the relation shown below?_. tupletupleRtuple S A) Union B) Difference C) Intersection D) Division (75) When embedding SQL in a C language program, the prefix that should be added to all SQL statements in order to distinguish SQL statements from the host language statements is_. A) ： B) EXEC C) EXEC SQL D) SQL (76) In the ORACLE system,sets of SQL statements and control flow statements that have been named,compiled,and stored tn the database are referred to as stored_. A) batches B) procedures C) triggers D) transactions (77) Which of the following statements about object oriented databases is NOT correct? _. (2分) A) Each object has a unique object identity in the system. B) Encapsulation and inheritance are two important features of object oriented databases. C) A subclass can inherit the attributes and methods of all its superclasses. D) A superclass includes the attributes and methods of all its subclasses. (78) In the design phase of software engineering, decomposition of the program into modules should follow the principles of _. A) low cohesion with low corpling B) low cohesion with high coupling C) high cohesion with low coupling D) high cohesion with high coupling C) (79) Specifications for software should contain&nbs p;several components, e.g., specifications of information flow, user interface, functional requirements, and design constraints. Two other important components are specifications of the_. (2分) A) methods of testing and ways to obtain quality assurance B) criteria for testing and ways to obtain quality assurance C) methods of testing and criteria for function assurane D) criteria for testing and methods of function assurance D) (80) Which of the following statements about testing software with data is (are) true?_. I. The primary purpose of such testing is to find errors. II. Such testing can demonstrate the existence of errors but cannot demonstrate the absence of errors. A) Neither B) only C) only D) and (81) The type of testing done during software implementation and beforemodule integration is called _. A) unit testing B) beta testing C) system testing D) acceptance testing (82) Which of the following is (are) true about software portability? _. I. Using a high-level language that conforms to an ISO standardguarantees portability across the range of machines that support the language. II. Portability is guaranteed across all machines that have the same instruction set and operating system. (2分) A) Neither B) only C) only D) and (83) A memory-memory, machine instruction for a certain machine has the following format. (Such an instruction is similar to a register-register instruction except that the operands are displaced addresses in memory.) opcode meml displ1 mem2 displ2 Which of the following could be an assembly lanuage instruction that would be translated into a memory-to-memory instruction for this machine? _. A) ADD 10(R1), 20(R2) B) ADD(10R1), (20R2) C) ADD R1, 10(R2), 20 D) ADD R1, 10, 20(R2) (84) In a certain cache system, the modified cache block is written to main memory only when the block is replaced. All of the following are used to describe this policy EXCEPT_. A) store-in B) write-back C) copy-back D) write-through (85) When an amount of memory is requested that is less than the size of a page, but a full page is allocated, the r esulting waste of memory is called _. A) external fragmentation B) internal fragmentation C) inaccessible page faults D) inaccessible garbage (86) The time that the CPU spends on a given program can be computed using all of the following expressions EXCEPT _. (2分) A) (CPU clock cycles for the program)*(clock cycle time) B) CPU clock cycles for the program clock rate C) (Instruction count)*CPI clock rate D) (CPU clock cycles for the program)*CPI clock rate (87) The methods used in Asynchronous Transfer Mode (ATM) are switch technology and which of the following is used to describe this mode?_. A) cell exchange B) packet exchange C) message exchange D) information exchange (88) In a data communication system, the transport media with the widest frequency band and best reliability is the _. A) telephone line B) coaxial cable C) radio channel D) fiber optic cable (89) Which of the following statements about the Internet is (are) true?_. I. It is possible to have multiple names corresponding to the same IP address. II. All host names must be registered with an Internet-wide central registry. A) Neither B) only C) only D) and (90) According to the principle of CRC calculation, given a frame-bit series M = and the multiple-term formula, frame-bit series generated by the CRC G =, then the CRC is _.(2分) A) B) 00011 C) D) 二、论述题(两个论述题可任选其一,并只选其一,多选无效,满分30分。) 论述题 1 局域网是当前计算机网络研究与应用的一个热点,而符合IEEE 802.3标准的传统Ethenet(MAC层采用CSMA/CD方法,物理层采用 10BASE-T标准)应用最为广泛。随着网络应用的发展,以及大型信息系统与多媒体技术的应用,人们对局域网性能提出了越来越高的要求,出现了符合 100BASE-T标准的Fast Ethernet、交换局域网Switching LAN与ATM等高速局域网产品。尽管高速局域网技术发展十分迅速,但是Ethernet仍然会被广泛地使用。今后的网络应该是传统Ethernet、 FastEthernet LAN与ATM共存的结构。因此,研究 Ethernet的基本工作原理、优点与缺点,讨论高速局域网络发展的趋势与特点,对我们学习和掌握局域网应用技术是十分重要的。 (1) 请用Ethernet发送与接收流程框图说明CSMA/CD介质访问控制方法的基本工作原理。(15分) (2) 为什么说CSMA/CD属于共享介质、随机争用型的介质访问控制方法?这种方法主要缺点是什么? (5分) (3) 你认为Fast Ethernet与ATM、Switching LAN是从哪两个方面改进了传统的Ethernet?它们各有什么优缺点? (10分) E) 论述题 2 进程通信就是进程之间进行信息交换。系统中各进程异步执行,但有些进程之间必须保持一定的联系,以便协调一致地完成指定任务。这种联系就是通过交换一定数量的信息来实现的。 消息缓冲通信技术是一种高级通信机制,由Hansen首先提出。其基本思想是:根据生产者消费者关系原理,利用公共消息缓冲区实现进程之间的信息交换。 (1) 试叙述高级通信机制与低级通信机制P、V原语操作的主要区别。(5分) (2) 试叙述解释消息缓冲通信技术的基本原理。 (10分) (3) 消息缓冲通信机制中提供发送消息原语。Send(receiver,a)和接收消息原语Receive(a)。调用参数a分别表示发送消息的内存区首地址 或接收进程的内存消息区首地址。试设计相应的数据结构,并用P、V操作原语实现Send和Receive原语。 (15分)F)他身背三角架，手拎仪器箱，每天起早贪黑，晴天一身汗，雨天一身泥，晚上记录复核到深夜geographic location Yibin city is located in beautiful rich of abundance-Sichuan basin South margin, is located in n 103 39 -105 20 , latitude 27