计算机专业英语第4次作业

Unit 4 Majors and Subjects / Why Is a Computer So Powerful课后习题答案（Keys to Task 4）1.Oral practice.Work in pairs and exchange the information about your majors and subjects.Omitted.2.Point out the conjunctions used in the following sentences.(1)When(2)If(3)and(4)and(5)but3.Choose the best answer from the given choices.(1) A(2) C(3) B(4) C(5) A习题册答案（Keys to the exercise book）Part One: Vocabulary 词汇用所给的词或短语的正确形式填空。

Part A1.favorite2.not only, but also3.interesting4.overcomemunicatePart B1.powerful2.carry out3.error4.dependable5.outputPart Two: Grammar & Function 语法与功能1.在右列中找出可与左列对应的句子。

(1) E(2) D(3) A(4) B(5) C2.从A、B、C、D选项中选择正确答案。

(1) C(2) D(3) C(4) C(5) C(6) D(7) C(8) A(9) B(10) CPart Three: Translation 翻译1.将下列短语翻译成英文。

(1)not only intelligent but also diligent(2)international language(3)overcome difficulties(4)billions of(5)information flow(6)error-free results2.将下列句子翻译成中文。

计算机专业英语作业：1、请将视频“什么是电脑硬件”中所述内容用英文表示。

2、请将以下英文翻译为中文。

1）Plug and Play, sometimes, abbreviated(简略的、缩写) PnP, is a catchy(动人的、易记住的) phrase( [freiz] 短语、习语) used to describe devices(设备、装备) that work with a computer system as soon as（与……一样）they are connected(链接的、有关系的). The user does not have to manually(手动的、用手) install drivers(驱动) for the device(装置、策略) or even tell the computer that a new device has been added. Instead the computer automatically(自动的、机械的) recognizes the device, loads new drivers for the hardware if needed, and begins to work with the newly connected device(链接设备)，即插即用，缩写为PnP，这是一个容易记住的短语，它用来描述与计算机操作系统连接工作有关的设备。

用户不需要为设备手动安装驱动，甚至于不需要告诉计算机已经添加了饿一个新的设备。

计算机自动识别设备，如果需要为硬件加载一个新的驱动，并且开始工作在新的连接设备上。

For example, if you connect a Plug-and-Play mouse to the USB port on your computer, it will begin to work within a few seconds of being plugged(拥塞的、接通电源) in. A non plug-and-play device would require you to go through several steps of installing drivers and setting up the device before it would work.例如，如果你在你的电脑上的USB接口连接了一个即插即用的鼠标，它开始工作时接通电源只需要几秒钟。

湖北职业技术学院2008-2009学年度第一学期期末考核试卷考核课程： 《计算机专业英语》 考试类型： 理论 考试方式： 闭卷笔试 学生所在院系： 信息技术学院 年 级： 2007 级 试 卷： A姓名: 班级： 学号：Ⅰ。

Translate the following phrases into English(将下列短语翻译成英语)（10％）1。

软件工程 （ )2。

算术逻辑运算 ( )3. 机器码 ( ）4。

帮助菜单 （ ）5。

图形技术 ( ）6. 中间件 （）7. 电子商务 （ )8。

办公自动化 ( ）9。

计算机病毒( )10。

可执行文件( )column with those similar in meaning in the right column （将左列的词汇与右列相应的汉语匹配)（10％）1. memory unit a. 半导体存储器2. intelligence b。

机制3。

semiconductor memory c。

存储单元4. data definition language d. 数据定义语言5. mechanism e。

通信6. machine language f。

机器语言7。

communication g。

智能8. element distance h。

桌面操作系统9。

desktop operating system i。

输入/输出设备10。

input/output device j.像素距离1。

（） 6. （）2. （） 7。

（）3。

（） 8。

（）4. ( ) 9. （）5。

( ） 10。

（ )Ⅲ. Fill in the blanks with the corresponding English abbreviations.（根据汉语写出相应的英语缩写） (10%）1. 只读存储器 _________ 6。

超文本标记语言_________2。

计算机专业英语全部答案(第三版)Unit1EX11 F2 T3 T4 F5 T6 F7 T 8 T 9 T 10FEX2Input hardware, storage hardware, processing hardware, output hardware power, speed, memorycentral processing unitinternal, primary, memorykeyboard, central processing unit, main memory, monitorEX3 PARTA1 F2 D3 G4 C5 B6 A7 E 8 HEX3 PART B1 F2 E3 G4 B5 A6 C7D 8 HEX41 input device2 screen3 manipulates4 instructions5 retrieve6 codes7 hardcopy8 functionEX51 T2 T3 F4 F5 T6 F7 T 8 TUNIT2EX11 T2 F3 T4 F5 T6 F7 T 8 FEX21 sizes, shapes, processing capabilities2 supercomputers, mainframe computers, minicomputers, microcomputers3 mainframe computer4 microcomputer, storage locations5 portables, laptop computers, desktop workstations6 semiconductor7 CPU, memory, storage, devices, processing, users8 microprocessor chipEX3 PARTA1 C2 A3 H4 I5 E6 F7 G 8 JEX3 PARTB1 capacity2 device3 laptop computer4 Portable computers5 Silicon6 semiconductor7 workstation8 Voltage, voltage9 RAM10ROMEX41 portable2 access3 main memory4 sophisticated programs5 processing capabilities6 instructions7 computation8 computer professionalEX51 T2 T3 F4 F5 F6 T7 F 8 T 9 T 10T11F 12T 13 T 14 TUNIT3EX11 T2 F3 T4 T5 T6 T7 F 8 F 9 T 10 F11T 12F 13F 14TEX21 microprocessor2 bus3 register 4control unit5 processor6 binary7 arithmetic, logic 8 milliseconds, microseconds9 instruction 10execution 11megahertz 12wordsize EX3 PARTA1 F2 A3 J4 C5 D6 E7 H 8 I 9 B 10GEX3 PARTB1 Storage 2chip3 buses4 ALU5 register 6control unit7 machine language 8 binary system 9 bits 10computer programEX41 configuration2 decodes3 data bus4 characters5 converts6 synchronize7 circuitry8 internal clockEX51 T2 F3 F4 T5 F6 F7 T 8 T 9 F 10 FUNIT4EX11 F2 T3 T4 F5 F6 T7 F 8 T 9 T 10 F11T 12T 13F 14F 15T 16F17T 18F 19T 20F21T 22FEX2memoryRAMdiskettes, diskschipsparityexpanded, extendedmonochromecacheROMupdatedEX3 PART A1 B2 E3 C4 J5 I6 H 7A 8 F 9 G 10DEX3 PART Bsecondary storagebufferaccesscodedisketteslotterminalsmotherboardbytescreenEX4desktopsoftwareanimationtransferredsophisticatedcompatiblecacheupgradeEX51 T2 F3 F4 T5 T6 T7 T8 F9 T 10 F11T 12F 13F 14T 15T 16F17F 18F 19F 20T21T 22TUnit 5Ex1:1 T2 T3 F4 T5 F6 F7 F 8 T 9 T 10 T11F 12T 13F 14F 15T 16T17F 18T 19F 20F21T 22T 23TEX2mail, courierhub, starlocal area networkpacketsEthernetkilobits per second, megabits per second, gigabits per second circuit switchingreassembledinternet protocol, transmission control protocol datagramsframesbinary, decimalEX3 part A1 C2 E3 B4 F5 A6 D7 H 8 GEX3 part Bhubzippeddecimalframebinary numberinternetpacketbandwidthEX4forwardedreassembledare encapsulatedcableburstysubmitare retransmittedprotocolEX5IP addressnotationdotted-decimalcomputer networkbackgroundsharedgeographicprivacyExercise to the Passage for ReadingEX6有意为维修技师使用所留被弃的、丢失的或损坏了的数据都进了数据桶。

计算机专业英语（第四版）课后习题答案Unit 1[Ex 1] 1. F 2. T 3. T 4. F 5. T 6. T 7. T 8. T 9. T 10. F[Ex 2] 1. input, storage, processing, and output 2. power;speed; memory3. central processing unit4. internal;primary; memory5. keyboard; central processing unit; main memory; monitor[Ex 3] A. 1. F 2. D 3. G 4. C 5. B 6. A 7. E 8. HB. 1. user 2. monitor 3. data 4. keyboard 5. data processing6. information7. computer8. memory[Ex 4] 1. input device 2. screen, screen 3. manipulates 4. instructions 5. retrieve6. code7. hard copy8. Function[ Ex. 5 ] 新处理器开始IT 技术的新时代New Processors Open New Era of IT TechnologiesLast week, Intel introduced to the public in Russia and other CIScountries a family of processors Intel Xeon E5-2600. They are more powerful and reliable and, importantly, are very economical in terms of energy consumption. Their presence opens a new era in the field of IT technologies and means that the cloud technology is getting closer.These processors are primarily designed for servers, data centers (DPC) and supercomputers. The emergence of this class of devices is not accidental. According tothe regional director of Intel in Russia and other CIS states Dmitri Konash who spoke at the event, the market of IT-technology is developing so rapidly that, according to forecasts, by 2015 there will be 15 billion devices connected to the Internet, and over 3 billion of active users .上周，英特尔公司向俄罗斯和其它独联体国家的公众推出了英特尔Xeon E5-2600系列处理器，它们更加强大可靠，尤其是在能量消耗方面更加经济实惠。

计算机专业英语教程第四版翻译课后练习题含答案简介《计算机专业英语教程》是针对计算机专业学生编写的一本英语教材。

本书旨在帮助学生通过学习计算机领域的专业英语词汇和语法，提升他们的英语能力和技能。

本文将为读者提供该教材第四版的课后练习题及答案。

第一课练习题1.将下列单词从易到难排序：chip, computer, algorithm, software,desktop2.将下列单词从中文翻译为英文：程序设计，硬件，操作系统，输入，输出3.请解释下列缩略语的全称：RAM，CPU，OS答案1.desktop, chip, computer, software, algorithm2.programming, hardware, operating system, input, output3.RAM（Random Access Memory），CPU（Central Processing Unit），OS（Operating System）第二课练习题1.请翻译下列句子：计算机的功能越来越强大，它可以执行许多任务。

2.请解释下列单词的意思：interface，protocol，server，router答案puters are becoming more and more powerful and they canperform many tasks.2.interface（接口）, protocol（协议），server（服务器），router（路由器）第三课练习题1.请将下列单词按字母顺序排列：database，file，program，server，storage2.请填写下列句子的空格：计算机会读取从硬盘 __ （into）内存。

3.请解释下列单词的意思：database，algorithm，client，browser答案1.algorithm，database，file，program，server，storage2.into3.database（数据库），algorithm（算法），client（客户端），browser（浏览器）第四课练习题1.请翻译下列句子：今天我学会了如何编写计算机程序。

《计算机专业英语》习题参考答案Lesson 1I.1. Operating System2. Fetch-evaluate-execute3. Front-side bus4. Dual-core processor5. Basic Input/Output System(BIOS)II.1. 指令是特定各式的二进制数列，它们对于每台机器都是唯一的。

2. CPU是中央处理单元的简称，每个字母分开发音。

3. 大多数计算在中央处理器中进行。

4. 双核是指一个处理器上有两个完整运算内核的CPU。

5. 处理器：是微处理器或CPU的缩写。

6. 集成电路：即芯片，是由半导体材料制成的一种电子设备。

III.1. F2. T3. TIV.1.ALU, CU, Register2.memory3.processor4.the CPULesson 2I.1.Static Random Access Memory(SRAM)2.Dynamic Random Access Memory(DRAM)3.Virtual Memory4.Physical Memory5.Level 1 Cache6.Level 2 Cache7.HDD access speedII.1.动态随机存储器之所以称为“动态”是因为它每秒钟被刷新数千次。

2.RAM：是计算机中存储操作系统、应用程序和当前正是用数据的地方。

3.ROM由计算机中一小块长寿命电池供电。

4.RAM缓存是由高速静态随机存储器构成的存储器。

III.1. F2. F3. F4. TIV.1. non-volatile2. compiler3. volatile4. DRAMLesson 3I.1. Motherboard2. PC Case3. Hard Disk Drive(HDD)4. Optical mouse5. RAM6. Mobile DiskII.1.PC是有很多组件构成的一个系统。

中译英参考答案Unit 1A computer system consists of hardware system and software system. The hardware of the computer is usually divided into three major parts or three primary subsystems: the CPU, the memory subsystem, and the I/O subsystem.The CPU performs many operations and controls computer. The memory subsystem is used to store program being executed by the CPU, along with the program’s data. The I/O subsystem allows the CPU to interact with input and output devices such as the keyboard and monitor of a personal computer. The components of the computer are connected to the buses.The part of the computer that performs the bulk of data processing operations is called the central processing unit and is referred to as the CPU. In microcomputer, it is often called the microprocessor. The CPU is made up of three major parts: control unit, ALU, and register set.Memory is also known as internal memory or main memory. It refers to the circuits in the computer that hold whatever programs and data are available for immediate use by the CPU.I/O subsystem includes I/O devices and interface. There are a wide variety of I/O devices, such as mouse, printer, sensor, disk, and so on. Input-output interface provides a method for transferring information between internal storage and external I/O devices. Peripherals connected to a computer need special communication links for interfacing them with the CPU. The purpose of the communication link is to resolve the differences that exist between the central computer and each peripheral.Unit 2Storage hardware provides permanent storage of information and programs for retrieval by the computer. Hard disk drives store information in magnetic particles embedded in a disk. Usually a permanent part of the computer, hard disk drives can store large amounts of information and retrieve that information very quickly.Although fixed hard drive systems offer faster access and have a higher storage capacity than optical discs, optical disc systems use removable media –a distinct benefit. Optical discs –primary CDs and DVDs – are much more widely used than removable hard drive systems. They are the standard today for software delivery, as well as commonly used for storing high-capacity music and video files. There are also versions of both CD and DVD drives available for home audio and home theater use. Optical discs are commonly referred to as compact discs.CD and DVD discs are read by CD and DVD drives. The speed of a CD or DVD drive is rated as 24x, 32x, 36x, and so on. These labels describe how fast the drive is compared to the first version of that drive. For example, a 36x drive is 36 times the speed of the baseline unit that was originally manufactured. Most optical discs have a title and other text printed only on one side and they are inserted into the drive with the printed side facing up. When inserting such a CD or DVD, be careful not to get dirt, fingerprints, scratches, or anything else that might hinder light reflectivity on the disc’s surface.Unit 3(a) A program is a list of instructions or statements for directing the computer to perform arequired data processing task. Programming is a multistep process for creating that list of instructions.(b) It is important to understand the difference between a class and an object of that class. A class is simply a specification for creating objects. Thus, a single class may create multiple objects.(c) Java is an object-oriented, network-friendly high-lever programming language that allows programmers to build applications that can run on almost any operating system.(d) ActiveX is a set of controls, or reusable components that enables programs or content of almost any type to be embedded within a Web page. Whereas a Java must be downloaded each time you visit a Web site, with ActiveX the component is downloaded only once, then stored on your hard disk for later, repeated use.(e) Programming involves a great deal of creativity. The design is guide to the function or purpose of each component, but the programmer has great flexibility in implementing the design as code. No matter what language is used, each program component involves at least three major aspects: control structures, algorithms, and data structures.Unit 4The software system can be divided into two broad categories: application software and system software. Application software consists of the program for performing tasks particular to the machine’s utilization. In contrast to application software, system software comprises a large number of programs. These programs start up the computer and function as the principle coordinator of all hardware components and application software. Without system software loaded into RAM of your computer, your hardware and application software are useless.System software can be grouped into three basic parts: operating system, utility software, and language translators. The majority of an installation’s utility software consists of programs for performing activities that are fundamental to computer installations yet not included in the operating system. In a sense, utility software consists of software units that extend the capabilities of the operating system.A computer’s OS is the main collection of programs that manage its activities. The primary chores of an OS are management and control. The OS ensures that all actions requested by a user are valid and processed in an orderly fashion. It also manages the computer system’s resources to perform these operations with efficiency and consistency.Application software is the software designed to help you solve problems specific to business or perform specific business tasks. Application software then is the layer of software closest to you. Basically, there are four categories of application software: productivity software, business and specialty software, entertainment software and education/reference software.Unit 5A computer network is often classified as being either a local area network (LAN), a metropolitan area network (WAN), or a wide area network (WAN). The connection of two or more networks is called an internetwork. The worldwide Internet is a well-known example of an internetwork.LANs are privately owned networks within a single building or campus of up to a few kilometers in size. They are widely used to connect personal computers and workstations incompany offices and factories to share resources and exchange information.In general, a given LAN will use only one type of transmission medium. Various topologies are possible for LANs. The most common LAN topologies are bus, ring and star.A MAN is basically a bigger version of a LAN and normally uses similar technology. MAN is designed to extend over an entire city. It may be a single network such as a cable television network, or it may be a means of connecting a number of LANs into a large network so that resources may be shared LAN-to-LAN as well as device-to-device. For example, a company can use a MAN to connect the LANs in all of its offices throughout a city.A W AN spans a large geographical area that may comprise a country, a continent, or even the world. It provides long-distance transmission of data, voice, image, and video information over large geographical area.In contrast to LANs, W ANs may utilize public leased, or private communication devices, usually in combinations, and can therefore span an unlimited number of miles.Unit 6Transmission media are used to transfer messages over a network. For instance, the transmission media used in a network may be a privately owned set of cables, the public phone lines, or a satellite system. Transmission media can either be wired or wireless.The three types of wired media most commonly used to carry messages are twisted-pair wire, coaxial cable, and fiber-optic cable. One of the most successful developments in transmission media in recent years has been fiber optics. Fiber-optic cable is commonly used for the high-speed backbone lines of a network, or for Internet infrastructure.Wireless transmission media have become especially popular in recent years. They support communications in situations in which physical wiring is impractical or inconvenient, as well as facilitate mobility. Wireless media are commonly used to connect devices to a network, to share information between computers, to connect wireless mice to a computer, and for handheld PCs, wireless phones, and other mobile devices. Radio signals transferred through the air are the heart of most types of wireless media. In addition to conventional broadcast radio application, the microwave, cellular, and satellite transmission media also use radio signals to transmit data.Radio transmissions require the use of a transmitter to send the radio signals through the air.A receiver (usually containing some type of antenna) accepts the date at the other end. When a device functions as both a receiver and transmitter, it is commonly called a transceiver or transmitter-receiver.Unit 7(a) Since many database systems users are not computer trained, developers hide the complexity from users through several levels of abstraction, to simplify user’s interactions with the system: physical level, logical level, and view level.(b) A database schema is specified by a set of definitions expressed by a special language called a data-definition language (DDL). The result of compilation of DDL statements is a set of tables that is stored in a special file called data dictionary, or data directory.(c) The structured query language (SQL) is the most widely used and standard query language for relational database management systems. It is a kind of non-procedural language.(d) An entity is a “thing”or “object”in the real world that is distinguishable from otherobjects. For example, each person is an entity, and bank accounts can be considered to be entities. Entities are described in a database by a set of attributes.(e) Data warehouse is one of the newest and hottest buzzwords and concepts in the IT field and the business environment. A data warehouse is a logical collection of information——gathered from many different operational databases——that supports business analysis activities and decision-making tasks.Unit 8Animation is the term used to describe a series of graphical images that are displayed one after the other to simulate movement. Cartoons on television are one example of animation.Video differs from animation in that it usually begins as a continuous stream of visual information that is broken into separate images or frames when the video is recorded. When the frames are projected—typically at a rate of 30 frames per second—the effect is a smooth reconstruction of the original continuous stream of information. As you might imagine, at 30 frames per second, the amount of data involved in displaying a video during a multimedia presentation can require a substantial amount of storage space. Consequently, video data—like audio data—is often compressed. A variety of compression standards exist. Some of the most common video file formats are .avi, .mpeg, .mov, .rm.For multimedia presentation, video may be recorded using a standard (analog) video camera and then converted to digital form as it is input into a computer. Alternatively, the film can be recording digitally using a digital video camera. Streaming video is frequently used on Web pages to reduce file size. Similar to streaming audio, Streaming video files can begin playing once a portion of the video has been downloaded.Unit 9(a) AI is currently being applied in business in the form of knowledge systems, which use human knowledge to solve problems. The most popular type of knowledge-based system is the expert system. An expert system is a computer program that attempts to represent the knowledge of human experts in the form of heuristics. The term heuristic is derived from the same Greek root as the word eureka, which means “to discover”.(b) The user interface enables the manager to enter instructions and information into the expert system and to receive information from it. The instructions specify the parameters that guide the expert system through its reasoning processing. The information is in the form of values assigned to certain variables.(c) The knowledge base contains both facts that describe the problem area and knowledge representation techniques that describe how the facts fit together in a logical manner. The term problem domain is used to describe the problem area.(d) An expert system, also called a knowledge-based system, is an artificial intelligence system that applies reasoning capabilities to reach a conclusion. Expert systems are excellent for diagnostic and prescriptive problems.(e) The DSS is not intended to replace the manager. The computer can be applied to the structured portion of the problem, but the manager is responsible for the unstructured portion——applying judgment or intuition and conducting analyses.Unit 10The linked list (see figure 1) consists of a series of nodes, which are not necessarily adjacent in memory. Each node contains the element and a link to a node containing its successor. We call this the next link. The last cell’s next link references null.To execute printList or find(x) we merely start at the first node in the list and then traverse the list by following the next links. This operation is clearly linear-time, as in the array implementation, although the constant is likely to be larger than if an array implementation were used. The findKth operation is no longer quite as efficient as an array implementation; findKth(i) takes O(i) time and works by traversing down the list in the obvious manner. In practice, this bound is pessimistic, because frequently the calls to findKth are in sorted order (by i). As an example, findKth(2), findKth(3), findKth(4), and findKth(6) can all be executed in one scan down the list.The remove method can be executed in one next reference change. Figure 2 shows the result of deleting the second element in the original list.The insert method requires obtaining a new node from the system by using a new call and then executing two reference maneuvers. The general idea is shown in figure 3. The dashed line represents the old next reference.figure 1figure 2figure 3Unit 11(a) A set is pure if all of its members are sets, all members of its members are sets, and so on. For example, the set containing only the empty set is a nonempty pure set.(b) A language is a describable set of finite strings, drawn from a fixed alphabet. A grammar is one way to "describe" the language. The grammar consists of a finite list of rules, where each rule replaces one substring with another. The string on the left must contain at least one nonterminal. The first string "produces" or "generates" the second. Thus a rule is also called a production.(c) A finite-state machine (FSM) or finite-state automaton（FA）is a mathematical abstraction sometimes used to design digital logic or computer programs. It is a behavior model composed of a finite number of states, transitions between those states, and actions, similar to a flow graph in which one can inspect the way logic runs when certain conditions are met.(d) Sometimes it is inconvenient or impossible to describe a set by listing all of its elements. Another useful way to define a set is by specifying a property that the elements of the set have in common. The notation P(x) is used to denote a sentence or statement P concerning the variable object x. The set defined by P(x) written {x | P(x)}, is just a collection of all the objects for whichP is true.Unit 12(a) Because drawings are typically displayed in 3D, CAD is especially helpful in designing automobiles, aircraft, ships, buildings, electrical circuits (including computer chips), and even clothing.(b) Computer-integrated manufacturing (CIM) is the manufacturing approach of using computers to control the entire production process. This integration allows individual processes to exchange information with each other and initiate actions. Through the integration of computers, manufacturing can be faster and less error-prone, although the main advantage is the ability to create automated manufacturing processes.(c) In addition to supporting decision making, coordination, and control, information system may also help managers and workers analyze problems, visualize complex subjects, and create new products.(d) Knowing the history and evolution of ERP is essential to understanding its current application and its future developments.(e) In addition to monitoring operational activities such as tracking the status of orders and inventory levels, enterprise system also improve organization-wide reporting and decision making.Unit 13(a) There are a wide variety of educational application programs available. Educational software is designed to teach one or more skills, such as reading, math, spelling, a foreign language, world geography, or to help prepare for standardized tests.(b) Electronic business (e-business) is the use of information technology and electronic communication networks to exchange business information and conduct transactions in electronic, paperless form.(c) Word processing software allows you to use computers to create, edit, store, and print documents. You can easily insert, delete, and move words, sentences, and paragraphs——without ever using an eraser.(d) What is a spreadsheet? Spreadsheet software takes its name from the accountant’s columnar worksheet, which it imitates. A spreadsheet is a worksheet consisting of a collection of cells formed by the intersection of rows and columns. Each cell can store one piece of information: a number, word or phrase, or formula.Unit 14(a) A geographic information system (GIS) is a system that captures, stores, analyzes, manages and presents data with reference to geographic location data. In the simplest terms, GIS is the merging of cartography, statistical analysis and database technology.(b) The GPS receiver uses the messages it receives to determine the transit time of each message and computes the distance to each satellite. These distances along with the satellites' locations are used to compute the position of the receiver. This position is then displayed, perhaps with a moving map display or latitude and longitude; elevation information may be included.(c) Virtual reality (VR) is a term that applies to computer-simulated environments that can simulate physical presence in the real world. Most current virtual reality environments areprimarily visual experiences, displayed either on a computer screen or through special stereoscopic displays, but some simulations include additional sensory information, such as sound through speakers or headphones.Unit 15(a) The software development process is sometimes called the software development life cycle (SDLC), because it describes the life of a software product from its conception to its implementation, delivery, use, and maintenance.(b) How can the CMM help your organization? There are three key roles the CMM plays. First, the CMM helps build an understanding of software process by describing the practices that contribute to a level of process maturity. The second role of the CMM is to provide a consistent basis for conducting appraisals of software processes. The CMM’s third key role is to serve as a blueprint for software process improvement.(c) The UML offers a standard way to write a system’s blueprints, including conceptual things such as business processes and system functions as well as concrete things such as programming language statements, database schemas, and reusable software components. The UML represents a collection of the best engineering practices that have proven successful in the modeling of large and complex systems.(d) Object modeling is a technique for identifying objects within the system environment and the relationships between those objects. The object-oriented approach to system development is based on several concepts, such as object, attribute, behavior, encapsulation, class, inheritance, polymorphism, persistence, etc.Unit 16“Security” is an all-encompassing term that describes all the concepts, techniques, and technologies to protect information from unauthorized access. There are several requirements for information security.Confidentiality: hiding data, usually with encryption, to prevent unauthorized viewing and access.Authenticity: the ability to know that the person or system you are communicating with is who or what you think it is.Access control: once a person or system has been authenticated, their ability to access data and use systems is determined by access controls.Data integrity: providing assurance that an information system or data is genuine.Availability: making sure that information is available to users in a secure way.To prevent unauthorized access, some type of identification procedure must be used. These vary from passwords to physical access object (access cards, etc.) to biometric devices that verify some type of personal characteristic, such as a fingerprint.Some of the most secure access control systems address both identification and authentication. Identification involves verifying that the person’s name or other identifying feature is listed as an authorized user; authentication refers to determining whether or not the person is actually who he or she claims to be.Unit 17A distributed system is a collection of independent computers which appear to the users of system as a single computer. Nearly all large software systems are distributed. For example, enterprise-wide business systems must support multiple users running common applications across different sites.A distributed system encompasses a variety of applications, their underlying support software, the hardware they run on, and the communication links connecting the distributed hardware. The largest and best-known distributed system is the set of computers, software, and services comprising the World Wide Web, which is so pervasive that it coexists with and connects to most other existing distributed systems. The most common distributed systems are networked client/server systems. Distributed systems share the general properties described below.●Multiple nodes●Message passing or communication●Resource sharing●Decentralized control●Concurrency or parallelism●Fault tolerance●Heterogeneity●OpennessDistributed systems have many inherent advantages, especially over centralized systems. Some applications are inherent distributed as well. In general, distributed systems:●Yield higher performance●Allow incremental growth●Allow one user to run a program on many different machines in parallel●Provide higher reliability。