北京大学计算机专业英语课件6.

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专业英语的时态特点
❖ 就时态而言，因为专业科技文献所涉及的内容 （如科学定义、定理、方程式或公式、图表等） 一般并没有特定的时间关系，所以在专业文献 中大部分都使用一般现在时。
❖ 至于一般过去时、一般完成时也在专业英语中 经常出现，如科技报告、科技新闻、科技史料 等。
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准确性
专业英语的准确性主要表现在用词上。然 而在语法结构上也有其特点。例如，为了 准确精细地描述事物过程，所用句子都较 长有些甚至一段就是一个句子。长句反映 了客观事物中复杂的关系，它与前述精练 的要求并不矛盾，句子长结构仍是精练的， 只是包含的信息量大，准确性较高。
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计算机专业英语的特点
❖常用It … 句型结构 ❖ 单个动词比动词词组用得频繁 ❖ 常使用动词或名词演化成的形容词 ❖ 希腊词根和拉丁词根比例大 ❖ 专业术语多 ❖ 半技术词汇多 ❖ 用虚拟语气表达假设或建议 ❖ 缩略语使用频繁
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专业英语的语法特点
❖客观（objectivity） ❖精练（conciseness） ❖准确（accuracy）
专业英语中的长句
❖ 面对长句，要进行语法分析。
❖ 语法分析主要从两点入手，第一是找出谓语，然后找 主语。一般英语句子不像汉语那样经常省略主语，而 是由主语和谓语一起构成句子的核心。
❖ 第二是找出连接词。英语和汉语的另一个不同是汉语 句子的分句之间常常没有连接词，而英语句子和分句 之间一般都有连接词连接。
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Unit 6 Section 2 Passage A
• algorithm • data structure • character • table • list • stack • queue • tree • array • node • LIFO • tail
• FIFO • hierarchy • vertex • edge • push • set • record • retrieval • element • multi-dimensional
• List
A list is a sequential data structure, i.e. a collection of items accessible one after another beginning at the head and ending at the tail. It can be stored in an array or as a sequence of linked nodes.
between the data. We can store the objects in real life into computer in the form of data information by using it. It really can help us write efficient programs. May be you will study this course next semester.
• Mr. Wu: Right. Requirements analysis is just the first step of
software engineering, and the designing, encoding and testing are just as important. You can refer to a lot of relevant infore’ll come to a systematic introduction in our future lessons. Go ahead with your website design contest. You can turn to me if you have any more questions.

management • Unit 27 Electronic Marketing • Unit 28 Computer Security
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Unit 1 Introduction of Computers
1.1 Text • A computer is a digital electronic
written off：注销；很快完成
as the price of progress：由于价格的进步
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Computer Development
• The Fourth Generation of Computers (1971 through now)
• First there was Large Scale Integration (LSI), with
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目录
• Unit 22 Artificial Intelligent • Unit 23 Neural Network • Unit 24 Introduction of Electronic
Commerce • Unit 25 Electronic Payment System • Unit 26 Logistics and Supply-chain
这是由一个主句和四个从句组成的复杂长句，只有进行必要的语法分析， 才能正确理解和翻译。现试译如下： 除非相信那些机器造出的产品卖给消费者的价格足够支付所有成本，否则 厂家是不会买那些机器的。 节译：要不相信那些机器造出的产品售价够本，厂家是不会买的。 后一句只用了24个字，比前句40个字节约用字40%，而对原句的基本内容 无损。可见，只要吃透原文的结构和内涵，翻译时再在汉语上反复推敲提 炼，复杂的英语长句，也是容易驾驭的。

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译文：
很难确切地说现代计算机是什么时 候发明的。从20世纪30年代到40年代， 制造了许多类似计算机的机器。但是这 些机器大部分没有今天我们所说的计算 机的所有特征。这些特性是：机器是电 子的，具有储存的程序, 而且是通用的。
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三：专业英语的专业性与客观性
1.由于专业英语的客观性，所以在文章中常常使 用被动语态。（占到3分之1到2分之一） 2.由于专业英语所涉及的内容没有特定的时间关 系，所以大部分都使用一般现在时。 3.专业英语中用尽可能少的单词来表达愿意，所 以常使用非限定动词、名词化单词或词组及其 他简化形式。
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Non-finite verb
非限定动词，也叫非谓语动词，在句中作谓语不能 单独。其中包括： 不定式(infinitive) 动名词(gerund) 动词+ing构成，具有名词和动词的 特性，在句中起名词的作用。 分词(participle) 分词为现在分词和过去分词。 现在分词有一般式和完成式。 一般式表示的动作和谓语的动作同时发生。 完成式表示的动作在谓语动词所表示的动作之前发 生。
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表语：
是用来说明主语的身份、状态，主要是说明主语“是什 么”或“怎么样”，由名词，代词，形容词，副词，介词短 语，不定式，从句等及相当于名词或形容词的词或短语来担 任。表语放在系动词之后。 E g: The weather has turned cold. You look younger than before. (adj.) We are friends. (n.) He isn’t in. (adv.) The two countries are at war now .(介词短语) My job is to teach them English.(不定式短语)

Acer E360 Socket 939 motherboard by Foxconn .svg
System Clock
Within the computer, events happen at a pace controlled by a tiny electronic “drummer”, called the system clock. The component is an electronic circuit that generated pulses at a rapid rate, measured in millions of cycles per second (MHz). Note that the system clock doesn’t have anything to do with keeping the time and date; the system clock synchronizes the computer’s internal activities. Synchronize : 同步
Control Unit
The control unit coordinates and controls all the other parts of the computer system. Under the direction of a program, the control unit manages four basic operations:
Power supply
A computer’s power supply can transform the alternating current (AC) available from standard wall outlets into the direct current (DC) needed for the computers operation. It also steps the voltage down to the low voltage required by the motherboard.

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RS flip-flop
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Shift registers
A register capable of shifting its binary information in one or both directions is called a shift register.
The simplest possible shift register is one that uses only flip-flops.
The output of a given flip-flop is connected to the D input of the flip-flop at its right. The clock is common to all flip-flops. The serial input determines what goes into the leftmost position during the shift. The serial output is taken from the output of the rightmost flip-flop.
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4-bit shift register
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The capabilities of shift register
▪ An input for clock pulses to synchronize all operations.
▪ A shift-right operation and a serial input line associated with the shift-right.

drive / draiv / n. 驱动器
I. Introduction
• An operating system (OS), in computer science, is the basic software that controls a computer. It has two major functions: it coordinates and manipulates computer hardware.
Computer hardware is the equipment involved in the function of a computer and consists of the components that can be physically handled. The function of these components is typically divided into three main categories: input, output, and storage. 计算机硬件设备参与功能的计算机并构成 的组件,这些组件可以被物理处理。这些组件的 功能通常分为三大类:输入、输出和存储。
light pen 光笔 stylus / 5stailEs / （[复]- luses 或 li / -lai / ）n. 输入笔，光笔
III. Output Hardware
• Output hardware consists of external devices that transfer information from the computer’s CPU to the computer user. A video display , or screen, converts information generated by the computer into visual information.

• Personal Digital Assistants: much smaller than even the subnotebooks. Personal Digital Assistants (PDAs) weypical PDA combines pen input, writing recognition, personal organizational tools, and communication capabilities in a very small package. Figure 1.2 shows an example of a PDA.
• Supercomputers are special, high-capacity computers used by very large organizations principally for research purposes. Among their uses are oil exploration and worldwide weather forecasting. An example of a supercomputer is shown in Figure 1.3.
••分析小 理型速：计度句算和中机数T，据h也 存ey被 储指称 能的为 力是中 介小型 于机 微型， 型计是 机算像 和机书 大；桌 型大 机短小 之语的间fa机。ll器中in。型b它公et们司we的或en处大 意思型是公“司的介部于门两一者般之把它间们”用，于i特n t殊he用ir途p。ro例ce如ss，in可g s以pe使e用ds它an们d做 data研-s究to或rin监g视ca某p一ac个iti生es产是过介程词。短小型语公作司状一语般。使用小型机进行一般
分析：in exchange for less weight 是介词短语作目的状 语，意思是“为了换取较轻的重量”。

代词：形容词和副词都有级的变化。用来代替名词、数词、短语或从句的词 叫代ቤተ መጻሕፍቲ ባይዱ。按其意义、特征及在句中的作用分为：人称代词、物主代词、指示 代词、反身代词、关系代词和不定代词等。
形容词及副词：形容词修饰名词，说明事物或人的性质或特征。副词主要用 来修饰动词、形容词、介词短语或其他副词。形容词和副词都有级的变化。 同等比较句型： 1）肯定句式：“A +谓语+ as +adj./adv.原级+ as + B”表示A与B一样。 2）否定句式：“A+谓语+not as(so)+adj./adv.原级+ as + B”表示A与B不同， 或A不如B。 比较级常用句型： 1）“A+谓语+adj./adv.比较级+ than +B”表示A比B更…… 2）“which is + adj./adv.比较级, A or B?”表示两者之间选择。 3）“adj./adv.比较级 + and + adj./adv.比较级”表示越来越……
including the keyboard, the mouse, and the scanner etc., output devices(See Figure 1-8～Figure 1-10)— including the monitor, the printer, the speakers etc., and secondary storage devices(See Figure1-11～Figure 1-13)— including
What is the Computer and the Internet?
Figure 1-1
Figure 1-2

• newsletter n： a short written report of news about a club, organization etc that is sent regularly to people who are interested:
(给特定读者定期寄发的) 业务通讯，简报 • Flyer n. a small sheet of paper advertising something: (广告)传单
• rendering n. A drawing in perspective of a proposed structure. 透视图：以透视画 法绘出的拟建建筑物的图案 • Landscape vt. ＝to make a park, garden etc look attractive and interesting by changing its design, and by planting trees and bushes etc: 美化景观
Commercial Programs, Shareware, Freeware
• Commercial software is copyrighted software you must pay for before you can use it. • Shareware refers to copyrighted software that you can use on a “try before you buy” basis. • Freeware (such as Linux OS) refers to copyrighted software given away for free with the understanding that you can‟t turn around and sell it for profit.