第一篇：计算机专业英语第4章
计算机专业英语教案第3章
博主目录 2009-06-18 22:58 阅读32 评论0
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第3章 Software Knowledge 3.1 Data Structures 3.2 Operating System 3.3 Programming Languages 3.4 Software Engineering
3.5 Software Testing and Maintenance
3.2 Operating System ? The purpose of an operating system is to provide an environment in which a user may execute programs. ? Operating systems exist because they are a reasonable way to solve the problem of creating a usable computing system. ? The primary goal of an operating system is convenience for the user. ? A secondary goal is efficient operation of the computer system. Resource Management
? The operating system provides the means for the proper use of these resources in the operation of the computer system. ? We can view an operating system as a resource allocates. ? The operating system sets up the order in which programs are processed, and defines the sequence in which particular jobs are executed ? I/O Management ? To facilitate execution of I/O operations, most operating systems have a standard set of control instructions to handle the processing of all input and output instructions.
? These standard instructions, referred to as the input/output control system (IOCS), are an integral part of most operating systems. ? The controlling software calls on the IOCS software to actually complete the I/O operation. Classification of Operating Systems
? A single-user operating system expects to deal with one set of input devices—those that can be controlled by one user at a time. ? A multi-user operating system is designed to deal with input, output, and processing requests from many users-all at the same time. ? A network operating system provides communications and routing services that allow computers to share data, programs and peripheral devices. ? A multitasking operating system provides process and memory management services that allow two or more programs to run simultaneously. ? All modern operating systems are multitasking and can run several processes simultaneously. ? A desktop operating system is one that is designed for a personal computer—either a desktop or notebook computer. ?
3.3 Programming Languages ? A programming language or computer language is a standardized communication technique for expressing instructions to a computer. ? A language enables a programmer to precisely specify what data a computer will act upon, how these data will be stored/transmitted, and what actions to take under various circumstances of cases. ? Programming languages are important tools for helping software engineers write better programs faster. Procedural programming and Object-oriented programming ? Procedural programming involves using your knowledge of a programming language to create computer memory locations that can hold values and writing a series of steps or operations that manipulate those values. ? A single procedural program often contains hundreds of variable and thousands of procedure calls. ? Object-oriented programming is an extension of procedural programming in which you take a slightly different approach to writing computer programs. ? Writing object-oriented programs involves both creating objects and creating applications that use those objects. Machine Language
? An executable program is a sequence of extremely simple instructions known as machine code. ? Machine code instructions are binary—that is, sequences of bits (0s and 1s). ? Because these numbers are not understood easily by humans, computer instructions usually are not written in machine code. Assembly Language
? Assembly language uses commands that are easier for programmers to understand than are machine-language commands.
? Each machine language instruction has an equivalent command in assembly language. ? Assembly language is sometimes inserted into a high-level language program to carry out specific hardware tasks or to speed up a high-level program. High-Level Languages
? If the computer could translate convenient symbols into basic operations, why couldn’t it also perform other clerical coding functions? ? A high-level programming language is a means of writing down, in formal terms, the steps that must be performed to process a given set of data in a uniquely defined way. ? The high-level languages are often oriented toward a particular class of processing problems. Compiler and Interpreter ? A complier is a program that translates source code into object code. ? Every high-level programming language comes with a compiler.
? Because compilers translate source code into object code, which is unique for each type of computer, many compilers are available for the same language. ? An interpreter translates high-level instructions into an intermediate form, which it then executes. ? The advantage of an interpreter, however, is that it does not need to go through the compilation stage during which machine instructions are generated. ?
3.4 Software Engineering ? Software engineering is the application of tools, methods, and disciplines to produce and maintain an automated solution to a real-world problem. ? Software engineering first emerged as a popular term in the title of a 1968 NATO conference held in Garmisch, Germany. ? A large-scale software projects spans a considerable period of time. A number of distinct phases can be identified over this period of time. Together, these make up what is known as the “software life cycle”.
The software life cycle
? Requirements definition: The requirements of the software are established and specified. ? Design: A design is developed from an analysis of the requirements. ? Implementation: The design is coded in a particular programming language on a particular machine. ? Testing: The implemented system is tested to see that it meets the specified requirements. ? Operation and maintenance: The system is installed and used. Errors found must be repaired. Requirements definition ? The first phase, requirements definition, refers to the period during which the requirements of the system desired, that is, it’s functional characteristics and operational details, are specified.
? The input to this phase is the stated (often rather loosely stated) needs for the software.
? Typically, a “requirements document” is the output of this phase, a set of precisely stated properties or constraints that the final product must satisfy. ? As with any of the phases, it is important that errors not be allowed to move into subsequent phases.
Design ? The second phase, design, is predominantly creative, while some would argue that creativity is inherent and cannot be trained or improved, it can certainly be enhanced by the use of good procedures and tools.
? The input to this phase is a (debugged and validated) requirements document: the output is a design expressed in some appropriate form (for example, pseudo-code).
? Each requirement in the requirements document must have a corresponding design fragment to meet it. Implementation ? The third phase, implementation, is the actual coding of the design developed in the second phase.
? The lure of this phase is strong, and many a foolhardy programmer has been drawn to it before adequately laying the groundwork in the first two phases.
? As a result, requirements are incompletely understood and the design is flawed. ? The implementation proceeds blindly, and many problems arise as a result. Testing
? The fourth phase, testing, is concerned with demonstrating the correctness of the implemented program. Inevitably some testing is performed as part of the previous two phases as well.
? Any experienced programmer mentally tests each line as it is produced and mentally simulates the execution of any module prior to any formal testing stage. ? A “successful” test run means only that no errors were uncovered with the particular circumstances tested; it says nothing about other circumstances.
? In theory, the only way that testing can show that a program is correct is if all possible cases are tried (known as an exhaustive test), a situation technically impossible for even the simplest programs.
Program maintenance
? The fifth phase is program maintenance phase. Student programmers, unfortunately, rarely become involved in this phase.
? Its importance in the real world, however, cannot be overemphasized, since the cost of maintaining a widely used program can match or exceed the cost of developing it.
? Unlike hardware maintenance, software maintenance deals not with repair of deteriorated components, but with repair of design defects, which may include the provision of added functions to meet new needs.
第二篇：税务会计第4章计算题参考答案
第4章计算题参考答案
1、
(1)进口化妆品应缴纳的关税=200×50%=100(万元)
(2)进口化妆品应缴纳的消费税=(200+100)/(1-30%)×30%=128.57(万元)
(3)乙公司代收代缴消费税=(100+20)/(1-30%)×30%=51.43(万元)
(4)甲公司销售化妆品应缴纳消费税=257.4/(1+17%)×30%-51.43×80%=24.86(万元)
2、
(1)本月甲企业向专卖店销售白酒应缴纳消费税
=(200+50+20)÷1.17×20%+20×2000×0.5÷10000=48.15(万元)
(2)乙企业已代收代缴消费税=(10+1)÷(1-10%)×10%=1.22(万元)
(3)本月甲企业销售瓶装药酒应缴纳消费税=1800×100÷10000×10%=1.8(万元)
(4)甲企业分给职工散装药酒不缴纳消费税。
3、
(1)卷烟厂进口环节应纳消费税=(30+6)/(1-30%)×30%=15.43(万元)
(2)卷烟厂应缴纳的消费税(不含进口环节应纳消费税)：
销售甲类卷烟应纳消费税=600×56%+300×50000×0.003/10000=340.5(万元) 销售乙类卷烟应纳消费税
=3600×36%+3600×50000×0.003/10000+18/(1+17%)×36%=1355.54(万元) 当月准予扣除外购烟丝已纳税款=150×2×30%=90(万元)
实际应缴纳的消费税=340.5+1355.54-90=1606.04(万元)
(3)烟草批发公司应缴纳的消费税=600×(1+20%)×5%=36(万元)
第三篇：高中英语句子翻译与写作 第4章 动名词
第四章动名词
历届试题
1.充分利用时间并不意味着从早到晚不停地看书。(keep) (S99)
2.进人大学以后，他对计算机很感兴趣。(become interested in) (Ss00)
3.集邮几乎占据了他所有的业余时间。(occupy) (Ss00)
4.早睡早起有益于身体健康。(do good to) (Ss01)
5.他很后悔失去了获得奖学金的机会。(regret) (Ss01)
6.勤洗手是避免疾病传染的有效方法之一。(infect) (S03)
7.我们盼望能参加下星期举行的艺术节开幕式。(look forward to) (Ss04)
8.多吃蔬菜和水果有益健康。(good) (S05)
9.在叔叔的帮助下，汤姆写成了一首动人的诗。(succeed) (Ss05)
10.医生挨家挨户上门巡访，省去了许多老年人去医院的麻烦。(save) (S07)
11.和园丁们一起工作让我们学到许多关于花卉的知识。(enable) (Ss07)
12.你擦一下窗，好吗?(mind)(Ss08)
13.只喝一杯咖啡就会使我整晚睡不着。(keep)(S09)
I. 作主语
1.适当引用一些谚语，能使你更容易表达你想讲的话。(quote)
2.你认为阅读能把别人从实践中学到的经验提供给我们吗? (provide)
3.在那偏僻的山区，辛勤劳动是摆脱贫穷的好办法。(freedom from)
4.学会骑自行车通常只需
一、二天时间。(take)
5.爬山大量消耗了我们的体力。(a great drain)
6.搞国际贸易势必要经常乘飞机。(involve)
7.把一个市分为几个区，给管理带来了便利。(bring convenience to)
8.去年在小山村里小住数日是我的一次激动人心的经历。(stay)
9.对于每一个人来说，尤其是老年人，心情好对健康有很大的好处。(do good to)
10.看太多的电视对孩子们没有好处。(do good)
11.不值得为这样的事与别人争吵，学会如何与别人相处是相当重要的。(get along with)
12.吃维生素片可以补充正常人所需要的某些重要营养。(make up for)
13.长寿没有秘诀，注意饮食、多运动肯定对健康有好处。(do good to)
14.我怀疑天天喝纯净水是否能满足常人对各种矿物质的需要。(meet)
15.很清楚，做这种事情意味着浪费时间。(mean)
16.一般说来，英语学习覆盖四种主要技能：听、说、读、写。(consist of)
17.养成一种爱好对一个人的身心健康有好处。(develop)
18.做一件毫无价值的工作就意味着浪费我们宝贵的时间。(mean)
19.对像他这样的研究生来说，用英语演讲根本就是小菜一碟。(to)
20.晚上喝一杯浓茶会让你整晚睡不着的。(keep)
21.如今，对于大多数岗位而言，具备电脑知识是一个重要资格。(equip)
22.保持工作与休闲的平衡有助于提高工作效率。(balance)
23.边开车边打手机是违反交通规则的。(against)
24.公共场所随地吐痰会导致疾病的传播。(spread)
II. 作表语
1.我的工作是教书，而他的工作是看病。(while)
III. 作宾语
1.放学后他没有直接回家，而是去一家餐馆做服务员。(instead of)
2.老教授花了毕生时间探索地球上的生命是如何起源的秘密。(search for)
3.我们盼望着被邀请参加在公园里举行的庆祝会。(look forward to)
4.这个男孩要当飞行员的梦想可能将有一天变成现实。(come true)
5.盲人用手指摸凸出的点子和划线来阅读。(by feeling)
6.谁也阻止不了这个计划的实行。(prevent)
7.那本书力争概要地说明中国历史。(aim at)
8.短暂的犹豫使他失去了赢得奥运会金牌的机会。(cost)
9.为了不让肥沃的土壤被雨水带走，我们就得种植足够的树。(carry away)
10.我还没有读完那本有关伦敦的书。(finish)
11.他没有跟我说一声就离开了山村。(without)
12.如果一个孩子说他想获得诺贝尔奖，你不能嘲笑他而应该鼓励他。(dream of)
13.这位老太太感谢警察帮她找到了她的手提包。(thank … for)
14.学生们通过在一起学习和玩耍而成了朋友。(by)
15.你讨厌住在火车站附近吗?(be bored with)
16.使我感到惊讶的是，世界上有些国家的人用摇头而不是点头来表示同意。(instead of)
17.非常感谢你邀请我参加你的生日晚会。(invite)
18.听到嘹亮的爱国歌曲，他感动了。(affect)
19.通过阅读旅游书籍，我们了解其他国家的情况。(gain information)
20.他处理不同人的意见的方法是很令人满意的。(deal with)
21.那个老人养成一种钓鱼取乐的业余爱好。(take up a hobby)
22.当一个人忙于生计时，不会想到业余爱好的。(make a living)
23.他想当医生的理想终于实现了。(come … true)
24.想着要为她父亲买件礼物，她就走进了百货商店。(think of)
25.老师花了许多时间倾听学生们的问题。(spend)
26.男孩们不停地吃，直到盘子里什么都不剩为止。(nothing left)
27.请你明天把你的词典带来给我好吗?(mind)
28.我们乐于帮助有困难的人。(enjoy)
29.我再请你帮个忙你不介意吧? (ask a favor for)
30.她的工作效率一点不高。(far from)
31.医生救了病孩，不使他因心脏病而死。(save … from)
32.他们坐在靠近火的地方来保持暖和。(stay warm)
33.你谈到的那个女演员远不是一个著名的电影明星。(far from)
34.你认为读词典能掌握更多的词汇吗? (a larger vocabulary)
35.他自己得出结论，而不是等待老师解释。(form … conclusion)
36.我不在乎花钱买这药，但我不知道这药对你是否有效。(mind)
37.因为在物理方面做出了重要发现，他得到了最高的荣誉。(make discovery)
38.这位年青人对写小说感兴趣，他对写作所得的报酬并不在意。 (take little notice of)
39.她很好地利用她在国外逗留的时间学习外语。(make good use of)
40.我们再怎么强调保护眼睛的重要性也不为过。(emphasize)
41.我一看书的目录就粗略地知道这本书的意思了。我不必把它从头读到底。 (get a rough
idea of)
42.我很感谢你为我搞到这些信息。(appreciate one’s kindness in)
43.他写信给他们询问是否可能在他们的大学里做几个月的研究工作。(write about the
possibility of)
44.他们盼望听到更多的古典音乐。(look forward to)
45.他一直工作，直到身体开始垮掉为止。(health began to fail)
46.他本想在店里消磨时间，但结果却买了各种各样他感兴趣的东西。(pass the time，end up
by)
47.我现在写信给你，询问是否有可能被允许到你的办公室来工作。 (write about the
possibility of)
48.由于那男孩在半夜练习拉小提琴，所有的邻居都抱怨太吵闹了。(complain of)
49.我盼着在圣诞晚会上见到你。(look forward to)
50.没有比奥运会开幕式更值得看的东西了。(worth)
51.有关方面已做了大量工作防止酸雨。(prevent … from … )
52.人们不接受左撇子，仅仅是因为大多数人习惯于用右手做许多事情。(accept，be
accustomed to)
53.面试时，教授向他提问，为的是了解他是否能胜任科学研究工作。(be capable of)
54.从它建立的那天起，联合国在维护世界和平方面就起了重要的作用。(play a role)
55.她对她的迟到怎么解释? (explain)
56.至于要说服他来嘛，那是完全不可能的。(question)
57.我们人类是自然之子。我们不应该和自然作对，而应该热爱和保护自然。 (struggle，
instead)
58.我们希望他能实现当医生的梦想。(come true)
59.滂沱大雨使约翰无法准时到达。(prevent)
60.我们非常感谢老师为我们提供许多好书。(grateful)
61.什么也阻止不了他实现自己的梦想。(prevent)
62.“你在意我把空调关掉吗?”“当然不在意。”(mind)
63.据说他很有可能出国继续深造。(possibility)
64.这种治疗方法似乎只针对身体的疾病，而不考虑病人的精神状态。(focus on)
65.Susan和Peter正在忙于安排他们的婚礼和蜜月。(arrangement)
66.我父亲花了毕生的时间探索地球上的生命是如何起源的秘密。(search for)
67.他没有意识到他在他的话中已伤害了她。(conscious)
68.跟大多数年轻人一样，他喜欢打篮球。(common)
69.我不得不表示遗憾，我不能参加你的婚礼了。(express regrets for)
70.为了完成这项任务，我们必须坚持不懈地克服困难。(persevere in)
71.我劝他戒烟，相反地，他却一直不停地抽烟。(on the contrary)
72.他一直梦想当一名演员，但他总是倒霉。(bad luck)
73.参观过展览会后，我们对新的铁路的建设有了一个大致的了解。(get … idea)
74.别叫车了，我走路无所谓的。(mind)
75.那个可怜的女孩很难把情况向警察解释清楚。(difficulty)
76.那个小女孩不习惯于在许多观众面前弹钢琴。(be used to)
77.他只是尝一下便能辨认出各种茶叶。(recognize)
78.人们模仿动物的行为和结构发明了许多有用的东西。(imitate)
79.那个地区严重缺水，村民们挖了许多口井来解决饮水问题。(lack)
80.他的病使他不能参加会议。(keep … from)
81.我们反对如此匆忙地离开。(object to)
82.我们正在考虑今年夏天去大连度假。(think about)
83.我记得我很小的时候被人带到这儿来过。(remember)
84.我忘了提醒你那件事，向他表示道歉。(remind)
85.什么也阻止不了中国的统一。(prevent)
86.毕业后，我将致力于为盲人服务。(devote)
87.你能给我推荐一名有能力用英语上物理课的老师吗?(recommend)
88.当你登上长城环顾四周时，你会情不自禁地为自己是一名中国人而自豪。 (can’t help)
89.非常感谢我不在的时候你对我孩子的照顾。(grateful)
90.你找到这所房子很费事吗? (trouble)
91.很多公司都在注重扩大他们的海外市场。(focus on)
92.许多家长担心他们的孩子整天热衷于打游戏机，对其他任何事物都不感兴趣。(be keen on)
93.他们必须自己下决心而不是我们为他们下决心。(instead of)
94.说老实话，我真后悔没有帮助他克服困难。(regret)
95.大约30年前，一支中国登山队着手准备攀登世界最高峰，最后成功了。(set about)
96.使我们失望的是申花队没能阻止对方进球。(prevent)
97.他踮起脚尖走进房间唯恐吵醒正在睡着的孩子。(awaken)
98.我们只有不断地学习，才能跟上现代科学的进步。(only by)
99.显然以少吃一顿饭来减肥的想法是很愚蠢的。(miss)
100.我们认为她完全能够照顾自己。(capable)
101.我国政府已经制定了法律，防止工厂向河流和湖泊排放污水。(prevent)
102.我打扰了你，向你表示道歉。(apologize)
103.顺便问一下，你考虑去听后天的音乐会吗? (attend)
104.通过广泛的阅读，我们可以获取有关历史、地理、科学等知识。(obtain)
105.像世界上其他语言一样，中文随着时代不断地变化。(keep)
106.我们要防止孩子们误把这些药片当成m&m巧克力。(mistake)
107.许多人一直梦想将来有一天能在月球上安家。(settle down)
108.我清楚地记得曾经见过这个人，但讲不清什么时候什么地点。(tell)
109.那个撞倒老奶奶的驾驶员承认开车前喝了酒。(admit)
110.她网球比赛输了，因为她不习惯与左撇子打球。(for)
111.在美国这样的西方国家，作家单靠写作来谋生是很难的。(make a living by)
112.你是否发现我们现在的购物习惯与二十年前完全不同了? (differ)
113.消防队在接到警报后三分钟就赶到现场，并立即控制了火势。(under contro1) 114.在会上100名热衷于当志愿者的市民受到了政府的表彰。(keen)
115.人们走上前去祝贺他在演讲比赛中获得第一名。(congratulate … on)
116.因为双方的分歧越来越大，他们认为这份协议已被毁弃。(regard)
117.在发展经济的过程中，我们必须注意节省资源和防止污染。(pay attention)
118.我从心底里佩服姚明的球艺和他对祖国的热爱。(admire)
119.在抗击“非典”的斗争中，许多医务工作者不考虑自己的安危，献身于救治工作。(without)
120.借着运动，我们能够始终保持健康。(stay)
121.不看电视我们也能知道世界大事。我们可以看报来获得消息。(go on)
122.下雨或下雪都不能阻止我去乡下探望爷爷。(neither … nor …)
123.作为班上的尖子学生，她有能力解答这些数学问题。(capable)
124.他们指控公司未能保护好公众的利益.(accuse)
125.不断上涨的油价使约翰打消了买车的念头。(gas prices)
126.我们必须不惜一切代价防止像非典、禽流感(bird nu)等的高发性传染性疾病的蔓延。
(spare)
127.我非常感激你的好心，给我们提供了这么多的第一手资料。(appreciate)
128.你能通过按这个按钮来调整电视的彩色。(adjust)
129.那老外的说话方式让我忍俊不禁。(can’t help)
130.两位宇航员在太空做成了多项科学实验。(succeed)
131.我很感激你们及时来营救了我的父母。(grateful)
132.这些广告旨在吸引消费者购买商品。(appeal)
133.你能想象汤姆在教室前面演讲的样子吗? (imagine)
134.他关上了窗以防雨水飘进来。(prevent)
135.他在业余时间里喜欢在因特网上与人聊天。(fond)
136.他十分感激您帮助他解决难题。(grateful)
137.你应该学会聚精会神地看书。(concentrate)
138.你应当独立思考，而不是一味地顺从他人。(instead)
139.由于我无法找到一个更好的方法解决这个问题，他建议我向父母求助。(suggest) 140.作为国内最好的足球队之一，我们队一路杀人决赛，最后才被击败。(all the way to)
IV.作定语
1.一位老人正手持拐杖在街上走。(stick)
第四篇：环境保护专业英语第十六章课文翻译
Type and Sources of Air Pollutants
空气污染物的类型和来源
What is air pollution? Air pollution is normally defined as air that contains one or more chemicals in high enough concentration to harm humans, other animals, vegetation or materials. 什么是空气污染 ?空气污染通常是指那种包含一种或多种化学物质富集到高浓度并足以伤害人类、其他动物、植物或材料的空气。
There are two major types of air pollution.主要有两种类型的空气污染 。
A primary air pollution is a chemical added directly to the air that occurs in a harmful concentration.初级空气污染是指有害的浓度直接进入到空气中的化学物质。It can be a natural air component, such as carbon dioxide, that rise above its normal concentration, or something not usually found in the air, such as a lead compound emitted by cars burning leaded gasoline. 这种化学物质可以是一个自然的空气成分，如超过了正常浓度的二氧化碳，，或通常不会在空气中发现的，如汽车燃烧含铅汽油所排放出来的主要尾气。
A secondary air pollution is a harmful chemical formed in the atmosphere through a chemical reaction among air components.次生空气污染是指在大气中由气体成分之间发生化学反应的有害化学物质。Serious air pollution usually results over a city or other area that is emitting high levels of pollutants during a period of air stagnation.严重的空气污染通常是因为一个城市或其他地区在空气流动停滞期间排放了高浓度污染物。The geographic location of some heavily populated cities, such as Los Angeles and Mexico City, makes them particularly susceptible to frequent air stagnation and pollution buildup.一些人口稠密的城市的地理位置，例如洛杉矶和墨西哥城，使他们特别容易受到频繁的空气停滞和空气污染累积的影响。
We must be careful about depending solely on concentration values in
determining the severity air pollutants.在仅从浓度来决定严重空气污染物方面，我们必须十分小心。 By themselves , measured concentrations tell us nothing about the danger caused by pollutants , because threshold levels , synergy, and biological magnification are also determining factors.通过测出的浓度自身并不能告知我们有关污染物所带来的危险的信息，因为临界浓度、协同作用还有生物放大效应都是决定因素。In addition, we run into the issue of conflicting views of what constitutes harm. 除此之外，我们碰到关于什么才构成危害的问题的争论。Major air pollutants following are the 11major types of air pollutants.以下11个主要类型的空气污染物是主要空气污染物： 1 .Carbon oxides: carbon monoxide, carbon dioxide.
1. 碳氧化物：一氧化碳，二氧化碳。 2. Sulfur oxides: sulfur dioxide, sulfur trioxide.
2. 硫氧化物：二氧化硫， 三氧化硫。
3. Nitrogen oxides: nitrous oxide, nitric oxide, nitrogen dioxide. 3. 氮氧化物：一氧化二氮 ， 一氧化氮 ， 二氧化氮.
4. Hydrocarbons (organic compounds containing carbon and hydrogen): methane, butane, benzene. 4.碳氢化合物(有机含有碳氢化合物)：甲烷丁烷苯。 5. Photochemical oxidants: ozone,PAN,andvarious aldehydes. 5.光化学氧化剂：臭氧，一组过氧酰基硝酸酯 和各种醛。
6. Particulates (solid particles or liquid droplets suspended in air): smoke, dust, soot, asbestos, metallic particles (such as lead, beryllium cadmium), oil, salt spray, sulfate salts. 6.颗粒(在空气中的固体颗粒或液滴悬浮)：烟雾，尘埃，烟尘，石棉，金属粒子(例如铅，镉铍)，石
油，盐雾，盐硫酸。 Type and Sources of Air Pollutants
空气污染物的类型和来源
What is air pollution? Air pollution is normally defined as air that contains one or more chemicals in high enough concentration to harm humans, other animals, vegetation or materials. 什么是空气污染 ?空气污染通常是指那种包含一种或多种化学物质富集到高浓度并足以伤害人类、其他动物、植物或材料的空气。There are two major types of air pollution.主要有两种类型的空气污染 。
A primary air pollution is a chemical added directly to the air that occurs in a harmful concentration.初级空气污染是指有害的浓度直接进入到空气中的化学物质。It can be a natural air component, such as carbon dioxide, that rise above its normal concentration, or something not usually found in the air, such as a lead compound emitted by cars burning leaded gasoline. 这种化学物质可以是一个自然的空气成分，如超过了正常浓度的二氧化碳，，或通常不会在空气中发现的，如汽车燃烧含铅汽油所排放出来的主要尾气。
A secondary air pollution is a harmful chemical formed in the atmosphere through a chemical reaction among air components.次生空气污染是指在大气中由气体成分之间发生化学反应的有害化学物质。Serious air pollution usually results over a city or other area that is emitting high levels of pollutants during a period of air stagnation.严重的空气污染通常是因为一个城市或其他地区在空气流动停滞期间排放了高浓度污染物。The geographic location of some heavily populated cities, such as Los Angeles and Mexico City, makes them particularly susceptible to frequent air stagnation and pollution buildup.一些人口稠密的城市的地理位置，例如洛杉矶和墨西哥城，使他们特别容易受到频繁的空气停滞和空气污染累积的影响。
We must be careful about depending solely on concentration values in determining the severity air pollutants.在仅从浓度来决定严重空气污染
物方面，我们必须十分小心。 By themselves , measured concentrations tell us nothing about the danger caused by pollutants , because threshold levels , synergy, and biological magnification are also determining factors.通过测出的浓度自身并不能告知我们有关污染物所带来的危险的信息，因为临界浓度、协同作用还有生物放大效应都是决定因素。In addition, we run into the issue of conflicting views of what constitutes harm. 除此之外，我们碰到关于什么才构成危害的问题的争论。Major air pollutants following are the 11major types of air pollutants.以下11个主要类型的空气污染物是主要空气污染物： 1 .Carbon oxides: carbon monoxide, carbon dioxide.
1. 碳氧化物：一氧化碳，二氧化碳。 2. Sulfur oxides: sulfur dioxide, sulfur trioxide.
2. 硫氧化物：二氧化硫， 三氧化硫。
3. Nitrogen oxides: nitrous oxide, nitric oxide, nitrogen dioxide. 3. 氮氧化物：一氧化二氮 ， 一氧化氮 ， 二氧化氮.
4. Hydrocarbons (organic compounds containing carbon and hydrogen): methane, butane, benzene. 4.碳氢化合物(有机含有碳氢化合物)：甲烷丁烷苯。 5. Photochemical oxidants: ozone,PAN,andvarious aldehydes. 5.光化学氧化剂：臭氧，一组过氧酰基硝酸酯 和各种醛。
6. Particulates (solid particles or liquid droplets suspended in air): smoke, dust, soot, asbestos, metallic particles (such as lead, beryllium cadmium), oil, salt spray, sulfate salts. 6.颗粒(在空气中的固体颗粒或液滴悬浮)：烟雾，尘埃，烟尘，石棉，金属粒子(例如铅，镉铍)，石
油，盐雾，盐硫酸。
7. Other inorganic compounds: asbestos, hydrogen fluoride, hydrogen s
ulfide, ammonia, sulfur acid, nitric acid. 7. 其他无机化合物：石棉，氟化氢，硫化氢，氨气，硫酸，硝酸。
8. Other organic compounds: pesticides, herbicides, various alcohols, acids, and other chemicals.
8.其他有机化合物：杀虫剂，除草剂，各种醇，酸和其他化学品。
9. Radioactive substances: tritium, radon, emissions from fossil fuel and nuclear power plants9.放射性物质：氚，氡，矿物燃料排放物和核能发电厂。 10. Heat.10. 热。Forest fires and decaying organic matter; incomplete combustion of fossil fuels (about two-thirds of total emissions) and other organic matter in cars and furnaces; cigarette smoke森林火灾和腐烂的有机物质;不完全燃烧矿物燃料(约占三分之二的总量)和其他来自汽车和炉的有机质;香烟烟雾
Carbon dioxide (CO2):Natural aerobic respiration of living organisms; burning of fossil fuels自然有氧呼吸的生物体; 燃烧化石燃料
Sulfur oxides(SO2 and SO3) ：Combustion of sulfur-containing coal and oil in homes, industries and Power plants;
smelting of sulfur-containing ores; volcanic eruptions 家庭、工厂和发电厂燃烧含硫的煤和石油;冶炼含硫矿石;火山爆发
Particulates dust soot and oil : 煤烟粉尘颗粒物和石油
forests fires , wind erosion, and volcanic eruptions; coal burning; farming, mining construction, road building ,and other land-clearing activities; chemical reactions in the atmosphere; dust stirred up by automobiles; automobile exhaust; coal-burning electric power and industrial plants森林火灾，风蚀，和火山爆发; 燃煤; 农业，采矿工程，道路建设，以及其他土地清理活动; 大气中的化学反应;汽车引发的粉尘 ;汽车尾
气;燃煤电力厂房和工业厂房Nitrogen oxides(NO and NO2):
High-temperature fuel combustion in motor vehicles and industrial and fossil fuel power plants; lighting 高温燃料燃烧机动车辆，工业和矿物燃料发电厂;照明 Photochemical oxidants光化学氧化剂
Sunlight acting on hydrocarbons and nitrogen oxides 碳氢化合物和氮氧化物在阳光下反应 Hydrocarbons碳氢化合物
Incomplete combustion fossil fuels in automobiles and furnaces; evaporation of industrial solvents and oil spills; tobacco smoke; forest fires; plant decay (about 85 percent of emissions ) 不完全燃烧化石燃料的汽车和火炉;蒸发的工业溶剂和石油泄漏;烟草烟雾;森林火灾;植物的腐烂(大约百分之85的排放) Pesticides and herbicides:
Agriculture; forestry; mosquito control农业;林业;蚊虫控制
Asbestos：石棉Asbestos mining; spraying of fireproofing insulation in buildings; deterioration ofbrakelinings石棉
开采;防火隔热建筑的喷漆;制动片的变质
Metals andMetalCompounds: 金 属 和 金 属 化合 物
Mining; industrial processes; coal burning; automobile exhaust挖掘;工业生产过程;燃煤;汽车尾气 Hydrogen Sulfide (H2S): Chemical industry; petroleum refining化学工业;石油炼制 Ammonia (NH3): Chemical industry; petroleum refining化学工业;石油炼制 Sulfuric Acid (H2SO4):
Reaction of sulfur trioxide and water vapor in atmosphere; Chemical industry三氧化硫和水汽在大气中反应; 化学工业
第五篇：电气工程及其自动化专业英语第6章6-1翻译
(第六章)
The modern society depends on the electricity supply more heavily than ever before. 现代社会的电力供应依赖于更多地比以往任何时候。 It can not be imagined what the world should be if the electricity supply were interrupted all over the world. 它无法想象的世界应该是什么，如果电力供应中断了世界各地。. 第一个完整的电力系统(包括发电机，电缆，熔断器，计量，并加载)的托马斯爱迪生所建-站纽约市珍珠街的历史始于1882年9月运作。 这是一个半径直流系统组成的一个蒸汽发动机驱动的直流发电机面积约1.5公里至59供电范围内的客户。负载，其中包括完全的白炽灯，为V提供110通过地下电缆系统。在一个类似的系统在大多数大城市在世界各地运行数年。随着马达的弗兰克斯普拉格发展在1884年，电机负载被添加到这些系统。这是什么开始发展成为世界上最大的产业之一。在最初的直流系统广泛使用尽管如此，他们几乎完全被空调系统所取代。到1886年，直流系统的局限性也日益明显。他们可以提供功率只有很短的距离从发电机。
为了保持发射功率损失(我2 R)和电压下降到可接受的水平，电压等级，必须长途输电高。如此高的电压不发电和电力消耗可以接受的，因此，电压转换成为一个方便的手段的必要性。
在发展的变压器，法国和交流输电由L.巴黎戈拉尔和JD吉布斯导致交流电力系统。
年，第一次在北美交流传输线将在俄勒冈州波特兰之间威拉梅特大瀑布和实施。
.这是一个单相线路传输功率为4,000公里，超过21 V系统的距离。随着交流的发展多相系统由尼古拉特斯拉，成为更具吸引力的。通过1888年，特斯拉举行交流多项专利电动机，发电机，变压器和输电系统。西屋公司购买了这些早期的发明专利，并形成了系统的基础，现在的交流。
在19世纪90年代，有很大的争议或交流电力行业是否应该统一于直流。到了世纪之交的，在交流系统赢得了原因出在下面的直流系统为：
1)电压水平可以很容易地改变了空调系统，从而提供了传输的灵活性，发电用不同的电压和消费。
(2)交流发电机简单得多比直流发电机。
(3)
(三)交流电机和电机便宜简单得多，比直流。
前三个阶段的美国北线投产于1893年- 1 2300五，南加州12公里路线研究。 I . 在电力传输初期交流，频率不规范。 有许多不同频率的使用：25，50，60，125，和133赫兹。这对互连的问题。最后60赫兹标准获得通过，成为美国在北美，虽然是50赫兹在许多其他国家使用。
较长的距离越来越需要大量的电力传输多激励他们逐步使用高压的水平。为了避免电压增殖数量无限，业界标准电压水平。在美国，标准是115，138， 161，和230千伏的高电压(高压)类，345，500和765千伏级的特高电压(超高压)。在中国，各级使用电压为10，35，110级高压， 220，中国330(仅在西北)和500千伏超高压类。
. 第一个750 kVtransmission线将建在不久的将来在中国西北地区。
随着交流的发展/直流转换设备，高压直流高压直流(HVDC)传输系统已经成为更具吸引力的经济和情况特殊。在高压直流输电可用于输电块以上的大长途电话，并提供不同系统间的异步连接在AC联网系统将是不切实际的，因为稳定考虑，或因标称频率的系统。
基本要求到电源系统是提供一个不间断的能源供应，以客户可接受的电压和频率。 由于电力无法大量储存在一个简单的方法和经济，电力的生产和消费必须同时进行。系统的故障或误操作的权力在任何阶段可能导致电力供应中断给客户。. 因此，一个正常的电力系统连续运行的，提供可靠的电力供应给客户的重要性是至关重要的。
(课后翻译)电力系统稳定，可广泛定义为干扰财产的权力系统，可继续经营的状态下正常运行的平衡条件和后向遭受恢复一个可以接受的平衡状态。
在电力系统的不稳定可能会表现在经营方式和多种不同的方式取决于系统配置。
传统上，稳定性问题一直是一个保持同步运行。由于电力系统的发电电力，一个令人满意的系统运行的必要条件是，依靠同步电机同步电机都留在同步或通俗的“步骤”。这一方面是受稳定的发电机转子的动态角度和功角的关系，然后提到“转子角稳定”。