请输入或粘贴题目内容
搜题
拍照、语音搜题，请扫码下载APP
题目内容
（请给出正确答案）
These vegetables can be cooked ______．
这些蔬菜可以用几种不同的方法烹调。
答案
更多“These vegetables can be cooked ______． 这些蔬菜可以用几种不同的方法烹调。”相关的问题
第1题
A．figure out
B．draw out
C．look out
D．work out
第2题
The first paragraph indicates that
A．eating chocolate is good for one"s heart
B．people doubt the good effect of eating chocolate
C．eating chocolate may prevent memory loss
D．people should not eat too much chocolate
第3题
But while people 【59】appear to be healthier and wealthier, an analysis of 【60】activities suggests they are also lazier. 【61】 the most popular pastime is watching television, with 98 percent of homes having【62】one set and over a third having a video recorder.
Other pastimes【63】 listening to music, gardening, sports, visiting friends or going out for a meal. The 56.8 million people of England, Scotland, Wales and Northern Ireland 【64】 an【65】 12 million household pets.
Most of the homes now have central heating, washing machines, refrigerators, telephones and even cars.
Britain are also 【66】. United Kingdom residents took over 17【67】holidays overseas in 1986, 【68】15.75 million in 1985, and the most popular destinations were 【69】 -Spain, France and Greece.
More people are eating meals out and【70】lifestyles have changed, the consumption of take - away meals, convenience foods and so - called fast food has also 【71】. Over the past 25 years, consumption of 【72】coffee, processed foods, fruit and vegetables has risen 【73】home consumption of beef, lamb, bread, potatoes, butter, sugar and tea has 【74】
Alcohol consumption is continuing its rise but the types of drinks taken has changed. Beer remains the most popular, but lager (淡啤酒) now【75】more than half of beer sales and there has been a switch from whisky to other spirits.
And those of us who survive and prosper can expect to live to the age of 71 for men and 77 for women - a year longer than in 1985.
(56)
A．looked after
B．cared for
C．better off
D．out of control
第4题
A meal containing fish and vegetables is considered a (health) ______ one.
第5题
Short Answers
1 Auctions are public sales of goods conducted by an officially approved auctioneer. He
asks the crowd assembled in the auction-room to make offers, or "bids", for the various
items on sale. He encourages buyers to b 记 higher figures, and finally names the highest
bidder as the buyer of the good. Practically all goods whose (lualities vary are sold by
auction. Among these are coffee, skins, wool, tea, furs, species, fruit and vegetables and
wines. Auction sales are also useful for land and property, antique furniture, pictures, rare
kooks, old china and works of art
2 An auction is usually advertised beforehand with full particulars of the articles to be
sold; and where and when they can be viewed by prospective buyers. TI the advertisement
cannot give full details, catalogues are printed, and each group of goods to be sold together,
called a "lot", is usually given a number. The auctioneer need not begin with Lot 1 and
continue in numerical order; he may wait until he registers the fact that certain dealers are in
the rocm and then produces the lots they are likely to be interested in. The auctioneer's
services are paid for in the form. of a percentage of the price the goods
are sold for. The
auctioneer therefore has a direct interest in pushing up the bidding as high as possible
3 The auctioneer must know fairly accurately the current market values of the goods
he is selling, and he should be acquainted with regular buyers of such goods. Fe will not
waste time by starting the bidding too low. He will also play on the rival among his buyers
and succeed in getting a high price by encouraging two business competitors to bid against
each other. It is largely in his advice that a seller will fix a "reserved" price, that is, a price
below which the goods cannot be sold. Even the best auctioneers, however, find it difficult
to stop a 'knock-out", whereby dealers illegally arranged themselves as the only bidder, in
the hope of buying goods at extremely low prices. If such a "knock-out" comes off, the real
auction sale takes place privately afterwards among the dealers
Questions31-35:
31. What are auctinns？
32. What are the goods which can be sold by auction？ (Name at least three)
33. Mhat is a "lot"？
34. How are the auctloneer, s services pa 记 for？
35. What wifl happen if a "knock-out" is achieved？
第6题
A、constitute
B、consist of
C、are composed of
D、include
第7题
Vegetables are cheap______when they are in season.
A．to buy
B．to buy them
C．buying
D．to be bought
第8题
A．altered
B．converted
C．fluctuated
D．modified
第9题
B.twice as many
C.as twice as many
D.more than twice as many
第10题
Which of the following statements is true about food？
A．Passengers had a lot of vegetables, but no fruit.
B．The sailors had four tins of beer a day.
C．The people on the ship often fell iii because of the lack of food.
D．The food for the passengers was more and better than that for the crew.
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”。
