专业英语复习(第五版)

1、2.1Optical Storage Media: High-Density Storage光存储介质：高密度存储Optical Laser Disk 光盘，激光盘CD-ROM 闪存光盘CD-R 只读存储器CD-RW 可读写光盘Magneto-Optical Disk 磁光盘DVDs (digital video disc) 数字化视频光盘4.2Using the Windows Operating System 使用windows操作系统GUI (graphical user interface) 图形化用户界面The Windows Interface Windows界面，窗口界面The

2、Desktop 桌面Windows 窗口Menus 菜单Checkmarks 记号Grayed-out Type 灰色显示类型Ellipses 省略Shortcut Keystrokes 键盘快捷方式Icon and Other Navigational Objects 图标及其他导航对象Icons 图标Toolbars 工具栏Menu Tabs 菜单选项栏Hyperlinks 超链接Dialog Boxes 对话框5.4.1Network Protocol 网络协议Protocol Hierarchies 协议分层ISO （International Organization for Sta

3、ndardization） 国际标准化组织OSI model 开房系统互连模型Network architecture 网络结构Peer 同等层Protocol stack 协议栈Layering and TCP/IP protocol 层和TCP/IP协议HDLC （High Level Data Link Communication）高层数据链路通信1. Physical 物理层2. Data link 数据链3. Network 网络层4. Transport 运输层5. Session 会议层6. Presentation 描述层7. Application 应用层8.2.3MP3 C

4、ompression MP3压缩MPEG(Moving Picture Experts Group) 动态图像专家组GHZ 千兆赫兹ADC 模/数转换器DAC 数/模转换器AM79C30A Digital Subscriber Controller 一种数字用户控制器SPARC station SPARC工作站Nyquist sampling theorem 尼奎斯特抽样定理PCM 脉码调制Huffman coding 哈夫曼编码15.1Software Development 软件发展Overview of Software Engineering 软件工程概述DFDs (data flow

5、 diagrams) 数据流图Process hierarchies 进程结构Software Engineer 软件工程师ATM (automated teller) 自动出柜机Tool kit 工具箱SE （Software engineering） 软件工程16.1What do I need to know about virusesFTP (file transfer protocol) 文件传输协议USB (universal serial bus) 通用串行总线架构anti-virus 防病毒，抗病毒virus scanner 病毒扫描程序3.2C+ and Object-Ori

6、ented Programming C+和面向对象程序Encapsulation 封装Class Hierarchy 类层次结构Inheritance 继承Polymorphism 多态性Virtual Functions 虚函数6.4Wireless Network 无线网络PC （personal computer） 个人电脑IEEE (Institute of Electrical and Electronic Engineers) 电气与电子工程师协会WAN (Wide Area Network) 广域网WLAN (Wireless WAN) 无线局域网DS (the Distribu

7、tion System) 分布系统AP (the ACCESS Point) 接入点BSS 基本服务组Infrared Technology 红外技术Bluetooth 蓝牙Wireless Ethernet 无线以太网WiMAX (world interoperability for microwave Access)全球微波接入互操作性Base station 基站PAN (Personal Area Network) 个人网MAN （Metropoliatan Area Network） 城域网WiFi (Wireless Fidelity) 基于IEEE802.11标准的无线局域网7.

8、2 Introduction to SQLSQL引言 Ideally, a database language must enable us to create the database and table structures;理想地，一个数据库语言必须使我们能够创建数据库和表结构；it must enable us to perform basic data-management chores (add, delete, and modify data);chores 困难的工作它必须使我们能够执行一些基本的日常数据管理工作（添加、删除和修改数据）；and it must enable u

9、s to perform complex queries designed to transform the raw data into useful information.raw 未加工的并且它必须使我们能够执行设计来把原始数据变换成有用信息的复杂查询。Moreover, it must perform such basic functions with minimal user effort, and its command structure and syntax must be easy to learn.此外，它必须让用户以最小的努力来完成这样一些基本功能，而且它的命令结构和语法必

10、须是易于学习的。Finally, it must be portable; that is, it must conform to some basic standard so that we do not have to learn from scratch when we move from one RDBMS to another.conform to 与.一致 learn from scratch 从头学起最后，它必须是可移植的，亦即，它必须与某个基本标准一致，以致当从一个RDBMS改变为另一个时不必要从头开始学习。 SQL meets these ideal database lan

11、guage requirements well.SQL很好地满足这些理想化的数据库语言需求。First, SQL coverage fits into three categories:首先，SQL覆盖范围归入三个范畴： 1. Data definition creates the database and its table structures. 数据定义创建数据库及其表结构。 2. Data management uses a set of commands to enter, correct, delete, and update data within the database ta

12、bles. 数据管理使用一组命令来对数据库表内的数据进行键入、校正、删除和更新。 3. Data query uses a set of commands to explore the database contents and allows the user to convert the raw data into useful information. 数据查询使用一组命令来探索数据库内容并使得用户能把原始数据转换成有用信息。 Second, SQL is relatively easy to learn: It performs the required database functio

13、ns by using a basic vocabulary of about thirty commands.其次，SQL是相当容易学的：它通过使用由大约30个命令组成的基本词汇表来执行所需的数据库功能。Better yet, SQL is a nonprocedural language: You merely have to command what is to be done; you don't have to worry about how it is to be done.还要好地，SQL是一个非过程式语言：你必须做的仅仅是发出要做什么的命令；不必操心它是如何做的。 Fi

14、nally, the American National Standards Institute (ANSI) does prescribe a standard SQL.prescribe 规定最后，美国国家标准协会（ANSI）规定了一个标准SQL。Never mind that the ANSI standard is so limited that all commerical SQL products exceed it.exceed 超过毋须介意，ANSI标准是如此有限制，以致所有的商用SQL产品都胜过它。In fact, some vendors already meet the

15、proposed ANSI SQL 2 standard, to be implemented in 1993.vendors 供应商 proposed 被提议的事实上，某些厂商已经符合要在1993年实施的所提议的ANSI SQL2标准Consequently, it is seldom possible to take a SQL-based application from one RDBMS to another without making some changes.因而，极少可能不做某些改变便把某个基于SQL的应用程序从一个RDBMS换到另一个RDBMS。Nevertheless,

16、the different SQL dialects share the same basic command set and structure, thus allowing us to conclude that there is a useable standard.dialects 方言不过，不同的SQL方言版本共享相同的基本命令集和结构，因此使我们能得出这样的结论：存在有一个可使用的标准。We will use this standard as the basis for our presentation.我们将使用这标准作为我们介绍的基础。But we will also pres

17、ent a few SQL enhancements, especially when those enhancements are widely shared among the many RDBMS vendors.然而，我们也将介绍几个SQL增强特性，特别是考虑到这些增强特性广泛地为很多RDBMS供销商所共有。 Don't become discouraged over the fact that several SQL dialects exist.discouraged 气馁的不要因存在几个SQL方言版本而气馁。Since the differences between th

18、e various SQL dialects are minor, you should have little trouble adjusting to your software requirements.因为各种SQL方言版本之间的差异是微小的，适应于你的软件需求几乎没有什么麻烦。Whether you use XDB, ORACLE, dBASEIV, DB2, R:BASE for DOS, IBM's OS/2 Database Manager, or any other well-established RDBMS software, our experience is

19、that a few hours spent with a software manual will be sufficient to get you up to SQL speed if you know the material presented in this chapter.sufficient 足够的 speed 加速不管你是使用XDB、ORACLE、dBASE 、DB2、Dos下的R： BASE、IBM的OS/2数据库管理程序，还是任何其他一致公认的RDBMS软件，我们的经验是：如果你了解本章中介绍的材料，对软件手册花上几个小时将足以使你成功地使用SQL。In short, th

20、e knowledge you again in this lesson is portable.简而言之，你在本章获得的知识是可用于他处的。 There are some very good reasons for studying SQL basics: 关于学习SQL基础，有几个很好的理由： 1. The ANSI standardization effort has led to a de faco query standard for relational databases. 1ANSI标准化努力已导致关系数据库的一个事实上的查询标准。 In fact, many relational database experts are inclined to argue that, "If it's not SQL, it's not relational." incline 倾向 事实上，很多关系数据库专家倾向于主张：“如果不是SQL，便不是关系型的”。 2. SQL has become the basis for present and expected future DBMS int