题目内容
（请给出正确答案）
A.accessible
B.avoidable
C.valuable
D.acceptable
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更多“Computer classes must be （）to …”相关的问题
A small percentage of girls making up the computer science classes would be ______.
A．100%
B．98%
C．10%
D．75%
A．Kim Lee
B．Pietro
C．Jennifer
D．Alessandro
Instead，they receive their elementary and high school education by working at home on computers.The Center for Education Reform. says the United States has 67 public “cyberschools.” and that is about twice as many as two years ago.
The money for students to attend a cyberschool comes from the governments of the states where they live.Some educators say cyberschools receive money that should support traditional public schools.They also say it is difficult to know if students are learning well.
Other educators praise this new form. of education for letting students work at their own speed.These people say cyberschools help students who were unhappy or unsuccessful in traditional schools.They say learning at home by computer ends long bus rides for children who live far from school.
Whatever the judgement of cyberschools，they are getting more and more popular.For example，a new cyberschool called Commonwealth Connections Academy will take in students this fall.It will serve children in the state of Pennsylvania from ages five through thirteen.
Children get free equipment for their online education.This includes a computer，a printer，books and technical services.Parents and students talk with teachers by telephone or by sending emails through their computers when necessary.
Students at cyberschools usually do not know one another.But 56 such students who finished studies at Western Pennsylvania Cyber Charter School recently met for the first time.They were guests of honor at their graduation.
1、What do we know from the text about students of a cyberschool？
A、They have to take long bus rides to school.
B、They study at home rather than in classrooms.
C、They receive money from traditional public schools.
D、They do well in traditional school programs.
2、What is a problem with cyberschools？
A、Their equipment costs a lot of money.
B、They get little support from the state government.
C、It is hard to know students' progress in learning.
D、The students find it hard to make friends.
3、Cyberschools are getting popular became().
A、they are less expensive for students
B、their students can work at their own speed
C、their graduates are more successful in society
D、they serve students in a wider age range
4、We can infer that the author of the text is().
A、unprejudiced in his description of cyberschools
B、excited about the future of cyberschools
C、doubtful about the quality of cyberschoois
D、disappointed at the development of cyberschools
Turing Award & ACM
图灵奖与美国计算机学会
Turing, Alan. M. (1912—1954) is famous as a British theorist of computer science. In 1936 he invented a machine, later called Turing Machine, which has become a crucial part of the foundation of modern computer science. Turing discussed his ideas for the future of machines in mechanizing mental processes: not only chess playing but also the possibility of machines capable of learning.
Turing's plan for the ACE[1]was approved in March 1946. Its main foree, however, was in programming ideas. Turing stressed, that the machine would require no reengineering—only new programming—for a wide range of acti.vities. Turing withdrew from the test in 1948, when nothing had actually been built. The Pilot ACE was later completed in 1950, and was in the vanguard of computing.
Turing' s progress lay in advancing computing ideas rather than practice. His underlying goals for computation, in which program modification played a vital part, appeared in his philosophical paper of 1950. This, including the imitation game operational definition of intelligence now known as the Turing test, is still regarded as the foundation of the philosophy of artificial intelligence[2].
Turing Award[3]
Turing Award was named for Alan M. Turing. Turing Award is the most prestigious technical recognition in the computer science field. It is sometimes referred to as[4]the "Nobel Prize" of computer science. The Association for Computing Machinery started bestowing this honor in 1966 to persons selected for their contributions to[5]computing. The Association for Computing Machinery is a New York-based scientific and educational organization of computer science professionals, with a worldwide membership of about 80,000.
Turing Machine[6]
The Turing machine isa mathematical construct, devised by Turing to specify precisely what should he understood by a mechanical process, what would nowadays generally be called an algorithm.
Turing's paper gave an analysis of what could be done by people acting mechanically. The key idea is that a machine may have finitely many configurations or states. A table of behavior then lays down precisely what the machine is to do in response to what it has read. Given[7]the general formalism, any particular Turing machine simply is the table of behavior.
Turing defined the term computable numbers[8]for those numbers that can be computed by a Turing machine. Turing's analysis picked out what is now known as the halting problem[8], which refers to predicting what an arbitrary Turing machine will do. It is shown that there is no Turing machine that can perform the required prediction.
Turing observed in his analysis that reading a table of behavior and interpreting the entries is itself a mechanical operation. This gave rise to his idea of the universal Turing machine, which is a particular kind of Turing machine that has a table of instructions that it will read the table of instructions of any other Turing machine and do what that Turing machine would have done. In modern terms, this is the function of a digital computer. Turing himself later extended this idea into the discussion of the possible mechanization of all mental processes. Turing machine is now an important concept in the cognitive sciences[10].
Turing Test
Turing test is an operational criterion for intelligence introduced by Turing in the paper "Computing Machinery and Intelligence", which is generally regarded as a founding contribution to the philosophy of artificial intelligence. The test, which Turing called the imitation game, is its most famous aspect.
The interrogator, a human, can communicate with two sources, one human and one machine. The interrogator mus decide which is which[11].
Figure 1 Turing Test
His proposal was as follows: Imagine you have a person able to communicate with two others, B and C, only through a teletype or computer link. This person must try to distinguish B from C simply by asking questions, while those being questioned try to fool the interrogator about their gender. In the Turing test, one of the human participants is replaced by a computer. If the computer is able to convince the interrogator it is the human, Turing argued, it can be said to be intelligent.
Turing's test presents the question "Can a machine think？" in a form amenable to experiment. It is intended to circumvent philosophical problems about the nature of mind by introducing an operational definition based on a materialist view[12]in which minds are identified with the functioning of the brain[13].
Turing's test is based entirely on observable output, avoiding the discussion of consciousness. However, many philosophers have continued to hold that human beings have an intrinsic quality that cannot be possessed even by a machine that successfully imitates human behavior. Other critics wonder whether digital information can be a satisfactory guide to intelligence. But Turing's game does have the merit of taking seriously the word intelligence.
The imitation game is only one aspect of Turing's paper, which has more constructive elements that put the ancient mind-matter problem in the scientific arena of the digital machine. Turing holds that computability is fundamental, argues that the action of the brain is computable, and that[14]a computer, as a universal machine[15]can do anything computable. He describes approaches to artificial intelligence through explicit programming and through implicit methods of teaching. Turing vividly illustrates the potential scope of machines as going beyond the mechanical in the everyday sense.
An Overview of ACM
The Association for Computing Machinery (ACM) is a major force in advancing the skills of information technology professionals and students. Founded in 1947, ACM is the largest and oldest international scientific and educational computer society in the industry todaY. Organized only a year after the unveiling of ENIAC, the first general-purpose[16]electronic computer, ACM was established by mathematicians and electrical engineers to advance the science and application of information technology. John Mauchly, co-inventor of the ENIAC, was one of ACM's founders. Since its inception, ACM has provided its members and the world of computer science a forum for the sharing of knowledge on developments and achievements necessary to the fruitful interchange of ideas. Over the years, ACM has flourished along with the industry itself[17], playing a major role in enriching the quality, form and function of computer usage.
The Importance of ACM.
Over the past 45 years ACM has played a vital role in disseminating the fruits of scientific efforts within and throughout the scientific and electronic engineering community. ACM' s founders understood the potential of the computer and were responsible for forming the early gathering points for exchange of data and ideas, and most of all, for stimulating others with their enthusiasm to learn and follow this exciting new endeavor.
ACM answered the need for a scientific and educational society to publish the latest scholarly opinions and briefs, to provide a forum for the interaction of ideas and concepts, and to consolidate the leadership of a new profession. Its Journal tied together the pioneering efforts on university and college campuses.
Much of the discussion after the earliest machines centered on programming—could a way better than basic binary machine code be found to instruct these new marvels？ And out of this, with help from ACM members, came FORTRAN and COBOL. ACM was the organization which provided the conferences, committee meetings and publications which gave impetus to these monumental efforts and provided the stimulus for integrity and high academic standards which have remained today as the guiding light and hallmark in computer science.
Nearly all the giants[18]of software development have been personally influenced by ACM membership—ACM publications—ACM Special Interest Groups—ACM Chapters and Student Chapters—ACM conferences... and virtually all academic computer science curricula used today stem from ACM's involvement in curricula creation and their efforts to maintain a consistently high level of content in computer science instruction.
Awards: ACM sponsors awards to recognize individuals for their technical and professional contributions to the field.
Turing Award. It is ACM's most prestigious technical award. It is given to an individual selected for contributions considered to be of lasting and major technical importance to the computer field.
Distinguished Service Award:The award is on the basis of value and degree of services to the computing community. The contribution is not limited to service to ACM itself, but includes activities in other organizations and emphasizes contributions to the computing profession at large.
Doctoral Dissertation[19]Award:This award is presented annually to the author(s) of the best doctoral dissertation(s) in computer science and engineering. The award includes ＄1000 plus royalties from sales of the published version.
Software System Award:It is awarded to an institution or individual(s) recognized for developing a software system that has had a lasting influence, reflected in contributions to concepts, in commercial acceptance, or both.
Outstanding Educator Award: Presented annually to an outstanding educator who is appointed to a recognized educational baccalaureate insti.tution and is recognized for advancing new teaching methodologies, effecting new curriculum development or expansion in Computer Science and Engineering, or making a significant contribution to the educational mission of the ACM. Those who have been teaching for ten years or less are given special consideration.
ACM Student Research Competition: Students from universities across the US and around the world can participate in this competition. ACM Special Interest Group, namely SIG[20]conferences offer additional opportunities for undergraduate students to demonstrate their research contributions and receive recognition for their work while encouraging graduate students to participate in computing research. They also enable students to interact with researchers in their respective fields and raise the profile of computing research within the IT community.
Notes
[1] ACE Automatic Computing Equipment自动计算机(装置)。
[2] ...the foundation of the philosophy of artificial intelligence人工智能基本原理的基础。
[3] Turing Award图灵奖(被誉计算机领域里的诺贝尔奖)。
[4] It is sometimes referred to as...有时它被誉为……。
[5] ...contributions to...对于……的贡献。注意：此处to为介词。
[6] Turing Machine图灵机(一种可不受存储容量限制的假想计算机)。
[7] given假设，假定。例如：
Given the condition of the engine,it is a wonder that it even starts.
倘若这台发动机能发动的话，可真是不可思议。
Given good health, I hope to finish the work this week.
倘若健康状况良好，我希望本周完成这项工作。
[8] computable numbers可计算数
[9] halting problem (of Turing machines)图灵机停机问题
[10] ...cognitive sciences认知科学。研究各种思维活动和过程，以及产生这些思维活动和过程的本质。
[11] The interrogator must decide which is which具体指The interrogator should be able to identify which one is human and which one is the machine.
[12] materialist view唯物主义观点。该理论认为物质实体是唯一现实存在。
[13] ...minds are identified with the functioning of the brain智力与大脑的作用有关。be identified with与……有关。例如：That politician is too closely identified with the former government to become a minister.
[14] ...and that... that为连接词，引导宾语从句，原文中相当于and argues that...。
[15] a universal machine通用机器。
[16] general purpose通用的。
[17] ACM has flourished along with the industry itself. ACM与(计算机)产业一样兴旺发达。
[18] giant此处应为名词，指“巨子、巨人”。
[19] doctoral dissertation博士论文。
[20] SIG：Special Interest Groups (of ACM)美国计算机协会的各类别专业组。
Evolution of Computer Architecture
计算机体系的演变
The study of computer architecture involves both hardware organization and programming/software requirements. As seen by an assembly language programmer, computer architecture is abstracted by its instruction set, which includes operation codes (opcode for short), addressing modes, registers, virtual memory, etc.
Legends:
I/E: Instruction Fetch and Execute
SIMD: Single Instruction Streams and Multiple Data Streams
MIMD: Multiple Instruction Streams and Multiple Data Streams Figure 1Tree Showing Architectural Evolution from Sequential Scalar Computers to Vector Processors and Parallel Computers
From the hardware implementation point of view, the abstract machine is organized with CPUs, caches, buses, microcodes, pipelines, physical memory, etc. Therefore, the study of architecture covers both instruction-set architectures and machine implementation organizations.
Over the past four decades, computer architecture has gone through evolutional rather than revolutional changes. Sustaining features are those that were proven performance deliverers, we started with the Von Neumann architecture[1]built as a sequential machine executing scalar data. The sequential computer was improved from bit-serial to word- parallel operations, and from fixed-point to floating-point operations. The Von Neumann architecture is slow due to sequential execution of instructions in programs.
Lookahead, Parallelism and Pipelining[2]
Lookahead techniques were introduced to prefetch instructions in order to overlap I/E (instruction fetch/decode and execution)[3]operations and to enable functiorial parallelism. Functional parallelism was supported by two approaches: One is to use multiple functional units simultaneously, and the other is to practice pipelining at various processing levels.
The latter includes pipelined instruction execution, pipelined arithmetic computations, and memory-access operations. Pipelining has proven especially attractive in performing identical operations repeatedly over vector data strings. Vector operations were originally carried out implicitly by software-controlled looping using scalar pipeline processors.
Flynn's Classification[4]
Flynn introduced a classification of various computer architectures based on notions of instruction and data streams in 1972. Conventional sequential machines are called SISD (single instruction stream over a single data stream)[5]computers. Vector computers are equipped with scalar and vector hardware or appear as SIMD (single instruction stream over multiple data streams)[6]machines. Parallel computers are reserved for MIMD (multiple Instruction streams over multiple data streams)[7]machines.
An MISD (multiple instruction streams and a single data steam)[8]machines are modeled. The same data stream flows through a linear array of processors executing different instruction streams. This architecture is also known as systolic arrays for pipelined execution of specific algorithms.
Of the four machine models, most parallel computers built in the past assumed the MIMD model for general-purpose computations. The SIMD and MISD models are more suitable for special-purpose computations. For this reason, MIMD is the most popular model, SIMD next, and MISD the least popular model being applied in commercial machines.
Parallel Computers
Intrinsic parallel computers are those that execute programs in MIMD mode. There are two major classes of parallel computers, namely, shared-memory multiprocessors and message-passing multicomputers. The major distinction between multiprocessors and multicomputers lies in memory sharing and the mechanisms used for interprocessor communication.
The processors in a multiprocessor system communicate with each other through shared variables in a common memory. Each computer node in a multicomputer system has a local memory, unshared with other nodes. Interprocessor communication is done through message passing among the nodes.
Explicit vector instructions were introduced with the appearance of vector processors. A vector processor is equipped with multiple vector pipelines that can be concurrently used under hardware or firmware control. There are two families of pipelined vector processors.
Memory-to-memory architecture supports the pipelined flow of vector operands directly from the memory to pipelines and then back to the memory. Register-to-register architecture uses vector registers to interface between the memory and functional pipelines.
Another important branch of the architecture tree consists of the SIMD computers for synchronized vector processing. An SIMD computer exploits spatial parallelism rather than temporal parallelism as in a pipelined computer. SIMD computing is achieved through the use of an array of processing elements synchronized by the same controller. Associative memory can be used to build SIMD associative processors.
Development Layers
Hardware configurations differ from machine to machine, even those of the same model. The address space of a processor in a computer system varies among different architectures. It depends on the memory organization, which is machine-dependent. These features are up to[9]the designer and should match the target application domains.
On the other hand, we want to develop application programs and programming environments which are machine-independent. Independent of machine architecture, the user programs can be ported to many computers with minimum conversion costs. High- level languages and communication models depend on the architectural choices made in a computer system. From a programmer's viewpoint, these two layers should be architecture-transparent.
At present, Fortran, C, Pascal, Ada, and Lisp[10]are supported by most computers. However, the communication models, shared variable versus message passing, are mostly machine-dependent. The Linda approach using tuple spaces offers any architecture- transparent communication model for parallel computers.
Application programmers prefer more architectural transparency. However, kernel programmers have to explore the opportunities supported by hardware. As a good computer architect, one has to approach the problem from both ends. The compilers and OS support should be designed to remove as many architectural constraints as possible from the programmer.
New Challenges
The technology of parallel processing is the outgrowth of four decades of research and industrial advances in microelectronics, printed circuits, high-density packaging, advanced processors, memory systems, peripheral devices, communication channels, language evolution, compiler sophistication, operating systems, programming environments, and application challenges.
The rapid progress made in hardware technology has significantly increased the economical feasibility of building a new generation of computers adopting parallel processing. However, the major barrier preventing parallel processing from entering the production mainstream is on the software and application side.
To date, it is still very difficult and painful to program parallel and vector computers[11]. We need to strive for major progress in the software area in order to create a user-friendly environment for high-power computers. A whole new generation of programmers need to be trained to program parallelism effectively. High-performance computers provide fast and accurate solutions to scientific, engineering, business, social, and defense problems.
Representative real-life problems include weather forecast modeling, computer-aided design of VLSI[12]circuits, large-scale database management, artificial intelligence, crime control, and strategic defense initiatives, just to name a few. The application domains of parallel processing computers are expanding steadily. With a good understanding of scalable computer architectures and mastery of parallel programming techniques the reader will be better prepared to face future computing challenges.
Notes
[1] the Von Neumann architecture: 冯·诺依曼体系结构，由匈牙利科学家Von Neumann于1946年提出。其基本思想是“存储程序”的概念，即把程序与数据存放在线性编址的存储器中，依次取出，进行解释和执行。
[2] Lookahead, Parallelism and Pipelining: 先行(预见)、并行性和流水线技术(管线)。
[3] I/E (instruction fetch/decode and execution)：取指令(指令去还)。
[4] Flynn Classification：弗林分类法，M.J. 弗林于1966年提出的、根据系统的指令和数据对计算机系统进行分类的一种方法。
[5] SISD(single instruction stream over a single data stream)：单指令单数据流(或single instruction single data).
[6] SIMD (single instruction stream over multiple data streams)：单指令多数据流(或single instruction multiple data).
[7] MIMD (multiple Instruction streams over multiple data streams)：多指令多数据流(或multiple Instruction multiple data).
[8] MISD (multiple instruction streams and a single data steam)：多指令单数据流(或multiple instruction single data).
[9] up to：应由某人担任或负责。如：It is up to them to decide. 应由他们决定。这一句可译为“这些特性由设计者考虑决定”。
[10] Fortran, C, Pascal, Ada, and Lisp: (分别是)Fortran语言、C语言、Pascal语言、Ada语言和Lisp语言。
[11] vector computers：向量计算机；向量电脑；一种数组计算机(an array computer)。
[12] VLSI: very large scale integration超大规模集成电路；大规模积体电路。
Night classes are _____.
A、a good idea
B、good ideas
C、good idea
D、the good idea
In China, passenger trains, as to classes, are divided into ().
A. soft seat
B. hard seat
C. soft couch
D. hard couch
