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A.result
B.factor
C.item
D.growth
答案
更多“The high cost of labor is an important ______ in the rising price of steel.A、resultB、”相关的问题
第1题
A.Because
B.excessively
C.gave up
D.over
第2题
Benefits of using VPNs include the following except ().
A、cost savings
B、extending connectivity to telecommuters,mobile users and remote offices
C、low security
D、high reliability
第3题
It is Henry Ford's belief that ______.
A．products should be made with less cost but higher efficiency
B．products should be sold at low prices in large quantity
C．products should be sold at high prices in large quantity
D．standards must be established in his plants
第4题
A．the lack of official support
B．its high cost
C．its failure to help increase production
D．the lack of financial support
第5题
A.The issue of understating poverty is especially pressing in the states with both a high cost and a high poverty rate such as California.
B.The poverty line lost all connection over time with current consumption patterns of the average family.
C.Many sociologists and government officials have argued that poverty in the US is understated.
D.The official poverty line today is essentially what it takes in today's dollars to purchase the same poverty-line level of living half a century ago.
第6题
A.Many sociologists and government officials have argued that poverty in the US is understated.
B.The poverty line lost all connection over time with current consumption patterns of the average family.
C.The issue of understating poverty is especially pressing in the states with both a high cost and a high poverty rate such as California.
D.The official poverty line today is essentially what it takes in today's dollars to purchase the same poverty-line level of living half a century ago.
第7题
What does Paragraph 3 mainly discuss？
A．The direction for future research.
B．The necessity of running more tests.
C．The difficulty of testing the theories.
D．The cost of animal experiments.
第8题
Lin: Glad to meet you again, James.
James: Hi, Lin．Glad to meet you, too．Are you prepared to start another round ？
Lin: I really have to say you are an expert in price negotiation．Have you got the feedback from your head office？
James: Yes, they still think your price is on high side, compared with what quoted by other suppliers.
Lin: As you know, the sustaining inflation and dull economic situation results in the increasing in the cost of raw material．Given the increasing cost of our production, our offer is very close to our bottom．And you know, as famous brand in this field, our silk products are of superior quality.
James: They are of the best quality, but we simply can't accept this price．Frankly speaking, two of your competitors have made us an offer at a price 10% lower than yours．After comparing samples, we believe the quality is similar．Buyers won't pay more for similar quality.
Lin: Our price is a bit higher, but the quality of our production is far superior to those of other competitors, it is not SIMILAR．Then what's the acceptable price in your mind？
James: Will you consider reducing your price by 10% ？
Lin: That's much more than we can do for you．But considering our long friendly business relationship, we are ready to reduce our price by 5 % if your quantity is not less than 5000 pieces．You know, business mainly rely on the size of your order.
James: We accept the quantity．But for this quantity, our final counter- offer requires a cut of 7%．I hope you'll consider it again.
Lin: Since it is a big order, I think we'll accept your price as an exception．It's quite a bargain.
James: If I place an order now, when would you be able to ship it ？
Lin: We should be able to get that off to you right away．Are you ready to place your order now？
James: The order will be mailed to you next week.
第9题
16. From the passage, we know that mobile homes _______.
A. can be built better than our homes
B. need to move all the time
C. can provide something people need
D. must stand only high on a hill
17. _______ is one of the reasons for people to choose mobile homes.
A. The job uncertainty
B. The strange design
C. The low price
D. The high speed
18. Which of the following may NOT attract people to buy mobile homes？
A. The new model appears every year.
B. Walls can be easily built around them.
C. They don't need to be painted.
D. They can be moved here and there.
19. We can infer that the increase of the mobile homes shows _______.
A. great changes in people's living style. (方式)
B. great interest in developing new things
C. some problems in people's life
D. people's hope for new jobs
20. Which of the following is the best title for the passage？
A. How to Choose a Mobile Home
B. The Developing Mobile Homes
C. The Uses of Mobile Homes
D. Mobile Homes Are Popular in the US
第10题
根据以下内容回答题：
Every couDle who goes to the altar（圣坛）believes that they will make that trip onlyonce in their lives．They want the day to be perfect，and they are asking for much more than good weather．Thev want the most beautiful clothes，the freshest flowers．Moreover，her family who will foot the bill is not in any mood，to economize． A quick look at any bride magazine will reveal that plenty of attractive goods and services compete for a share of the wedding budget．Besides the obvious choices of rings，dresses，flowers，and photographs，there are the less apparent expenses：a lavish（奢侈的）cake，a rehearsal dinner，a reception，music fbr both the ceremony and the reception，tips，and even nadkins and matchbooks printed with the couple’s names and the wedding date． As the arrangements are generally complicated，there are plenty of services that can be hired to helD with the planning and execution of the every aspect of the wedding：planning the photographs，selecting the wedding rings，choosing the flowers，picking the honeymoon spot，and so on．One magazine lists over 350 such pamphlets published，of course，by businesses who have something to offer．Considering that weddings do more than l 2 billion dollars worth of business annually in the US alone，such activity isn’t surprising． What is surprising is that not one company dominates the industry．It seems that when people plan for a day as special to them as a weddin9，they resist standardization．They turn instead to the small local suppliers known to them or to their friends．Family members or friends often servee as Dhotographers，caterers and musicians．This．not only helps bring the wedding cost down，but makes it more personal． What about the couple that doesn’t want to take in this billion-dollar industry？They can go to eity hall and get married for less than the price of a hamburger．
What does the expression“this billion．dollar industry”refer to？
A.The budgets of weddings．
B.The business ofweddings．
C.The planning and execution of weddings
D.The high wedding expenses．
第11题
Distributed Systems
分布系统
Computer systems are undergoing a revolution. From 1945, when the modern computer era began, until about 1985, computers were large and expensive. Even minicomputers normally cost tens of thousands of dollars each. As a result, most organizations had only a handful of computers, and for lack of a way to connect them, they operated independently from one another.
Starting in the mid 1980s, however, two advances in technology began to change that situation. The first was the development of powerful microprocessors. Initially, these were 8 bit machines, but soon 16, 32, and even 64 bit CPUs became common. Many of these had the computing power of a decent-sized mainframe (i. e. large) computer, but for a fraction of the price.
The amount of improvement that has occurred in computer technology in the past half century is truly staggering and totally unprecedented in other industries. From a machine that cost 10 million dollars and executed 1 instruction per second, we have come to machines that cost 1,000 dollars and execute 10 million instructions per second, a price/ performance gain of 1011. If cars had improved at this rate in the same time period, a Roll Royce would now cost 10 dollars and get a billion miles per gallon. (Unfortunately, it would probably also have a 200 page manual telling how to open the door.) The second development was the invention of high speed computer networks. The local area networks, or LANs, allow dozens, or even hundreds, of machines within a building to be connected in such a way that small amounts of information can be transferred between machines in a millisecond or so. Larger amounts of data can be moved between machines at rates of 10 to 100 million bits/sec and sometimes more. The wide area networks, or WANs, allow millions of machines all over the earth to be connected at speeds varying from 64Kbps (kilobits per second) to gigabits per second for some advanced experimental networks.
The result of these technologies is that it is now not only feasible, but easy, to put together computing systems composed of large numbers of CPUs connected by a high speed network. They are usually called distributed systems, in contrast to the previous centralized systems (or single processor systems) consisting of a single CPU, its memory, peripherals, and some terminals.
There is only one fly in the ointment[1]: software. Distributed systems need radically different software than centralized systems do. In particular, the necessary operating systems are only beginning to emerge. The first few steps have been taken, but there is still a long way to go. Nevertheless, enough is already known about these distributed operating systems that we can present the basic ideas.
What Is a Distributed System？
Various definitions of distributed systems have been given in literature, none of them satisfactory and none of them in agreement with any of the others. For our purposes it is sufficient to give a loose characterization.
A distributed system is a collection of independent computers that appear to the users of the system as a single computer.
This definition has two aspects. The first one deals with hardware: the machines are autonomous. The second one deals with software: the users think of the system as a single computer. Both are essential.
Rather than going further with definitions, it is probably more helpful to give several examples of distributed systems. As a first example, consider a network of workstations in a university or company department. In addition to each user's personal workstation, there might be a pool of processors in the machine room that are not assigned to specific users but are allocated dynamically as needed. Such a system might have a single file system, with all files accessible from all machines in the same way and using the same path name. Furthermore, when a user typed a command, the system could look for the best place to execute that command, possibly on the user's own workstation, possibly on an idle workstation belonging to someone else, and possibly on one of the unassigned processors in the machine room. If the system as a whole looked and acted like a classical single processor timesharing system, it would qualify as a distributed system.
As a second example, consider a factory full of robots, each containing a powerful computer for handling vision, planning, communication, and other tasks. When a robot on the assembly line notices that a part it is supposed to install is defective, it asks another robot in the parts department to bring it a replacement. If all the robots act like peripheral devices attached to the same central computer and the system can be programmed that way, it too counts as a distributed system.
As a final example, think about a large bank with hundreds of branch offices all over the world. Each office has a master computer to store local accounts and handle local transactions. In addition, each computer has the ability to talk to all other branch computers and with a central computer at headquarters. If transactions can be done without regard to where a customer or account is, and the users do not notice any difference between this system and the old centralized mainframe that it replaced, it too would be considered a distributed system.
Advantages of Distributed Systems over Centralized Systems
The real driving force behind the trend toward decentralization is economics. A quarter of a century ago, computer pundit and gadfly Herb Grosch stated what later came to be known as Grosch's law: the computing power of a CPU is proportional to the square of its price. By paying twice as much, you could get four times the performance. This observation fit the mainframe technology of its time quite well, and led most organizations to buy the largest single machine they could afford.
With microprocessor technology, Grosch's law no longer holds. For a few hundred dollars you can get a CPU chip that can execute more instructions per second than one of the largest 1980s mainframes. If you are willing to pay twice as much, you get the same CPU, but running at a somewhat higher clock speed. As a result, the most cost effective solution is frequently to harness a large number of cheap CPUs together in a system. Thus, the leading reason for the trend toward distributed systems is that these systems potentially have a much better price/performance ratio than a single large centralized system would have. In effect, a distributed system gives more bang for the buck[2].
A slight variation on this theme is the observation that a collection of microprocessors cannot only give a better price/performance ratio than a single mainframe, but may yield an absolute performance that no mainframe can achieve at any price. For example, with current technology it is possible to build a system from 10,000 modern CPU chips, each of which runs at 50 MIPS (Millions of Instructions Per Second), for a total performance of 500,000MIPS. For a single processor (i. e. CPU) to achieve this, it would have to execute an instruction in 0. 002 nsec (2 picosec). No existing machine even comes close to this, and both theoretical and engineering considerations make it unlikely that any machine ever will. Theoretically, Einstein's theory of relativity dictates that nothing can travel faster than light, which can cover only 0.6 mm in 2 picosec. Practically, a computer of that speed fully contained a 0.6 mm cube would generate so much heat that it would melt instantly. Thus, whether the goal is normal performance at low cost or extremely high performance at greater cost, distributed systems have much to offer.
As an aside, some authors make a distinction between distributed systems, which are designed to allow many users to work together, and parallel systems, whose only goal is to achieve maximum speedup on a single problem, as our 500,000 MIPS machine might. We believe that this distinction is difficult to maintain because the design spectrum is really a continuum. We prefer to use the term "distributed system" in the broadest sense to denote any system in which multiple interconnected CPUs work together.
A next reason for building a distributed system is that some applications are inherently distributed. A supermarket chain might have many stores, each of which gets goods delivered locally (possibly from local farms), makes local sales, and makes local decisions about which vegetables are so old or rotten that they must be thrown out. It therefore makes sense to keep track of inventory at each store on a local computer rather than centrally at corporate headquarters. After all, most queries and updates will be done locally. Nevertheless, from time to time, top management may want to find out how many rutabagas it currently owns. One way to accomplish this goal is to make the complete system look like a single computer to the application programs, but implement decentrally, with one computer per store as we have described. This would then be a commercial distributed system.
Notes
[1] There is only one fly in the ointment. 美中不足。
[2] gives more bang for the buck: buck，俚语，表示—美元。这句的意思是“小钱办大事”。
