Understanding the Text Choose the best answer for each of the following questions according to the text.
What are computers?
1.Since their first appearance on earth, men have gathered information and have attempted to pass useful ideas to other men. The carving 1 of word-pictures on the walls of ancient caves as well as hieroglyphics on stone tablets represent some of men's earliest efforts to convey information. Scenes of hunting, maps of battles, and the stories of heroes were put down for all to see.
2.But as civilizations grew more complex, better methods of communication were needed. The written word, carrier pigeons, the telegraph, and many other devices carried ideas faster and faster from man to man. In recent years one type of machine, the electronic computer, has become increasingly important in the lives of all the people in the industrialized 6 nations of the world. Computers are now widely used aids for communication, calculation ,and other activities. Their effect becomes more important every day.
3.Man has always been interested in extending the range of his senses and the power of his mind. Through the years, he has invented many instruments to help him see better and understand more,The telescope, for example，was invented away objects. To see the very small things in the world, the microscope was developed.Radio, telephone, and telegraph are means by which man has extended the range of his senses of hearing and speech.
4.While developing his power of thought, man first began to identify and count objects. He began to ask the questions "What is it?" and "How many?". It was a long time ago that this numbering and comparing of things began.
5.New ways of helping with counting and recording information evolved. Marks of different kinds were taken to represent certain quantities, and other marks were taken to represent relationships between quantities.
6.New devices to aid in the manipulation of numbers were developed.
7.Electronic computers are among the fastest and most useful instruments for sorting and comparing in use today. Computers provide the means for greater speed and accuracy in working with ideas than had previously been possible. With the development of these new tools, it is as if man has suddenly become a millionaire of the mind.
8.Although man has been growing mentally richer ever since he started to think, the electronic computer allows and will continue to allow him to perform tremendous "mental" tasks in a relatively short time. Great scientists of the past produced ideas which were the basis for great advances, but their ideas sometimes had to wait for years before they were understood sufficiently well to be of practical use. With the computer9 the ideas of today's scientists can be studied, tested, distributed, and used more rapidly than ever before.
9.Old lines and methods of communication do not work easily or efficiently with as much information as we have now. The repeated actions of preparing, sorting, filling, distributing,and keeping track of records and publications can be as troublesome as calculating. Errors occur because men grow tired and can be distracted.
10.The basic job of computers is the processing of information.For this reason computers can be defined as devices which accept information, perform mathematical or logical operations with the information, and then supply the results of these operations as new information.
11.Although a sharp dividing line between types of computers is not always easy to see, computers are usually divided into two broad groups： digital and analog. Digital computers work by using specific information which is usually in the form of numbers. Analog computers, on the other hand, usually process continuous information.
12.To explain this difference, let us consider two devices which handle information in a manner similar to the two types of computers. A turnstile,which has a counter attached to it, can help to explain the way a digital computer works. Each time a person passes through the turnstile, the indicator quickly jumps from one number to another. Each number registered is separate and specific.
13.The continuous change in the level of sand in an hourglass as time passes makes it an analog device. Perhaps the first analog computation was the use of graphs for the solution of surveying problems.
14.Among the first analog computers was the one set up by Lord Kelvin in 1872 to predict the height of tides in English harbors. The machine contained pulleys, levers, and weights whose actions imitated the effect of winds,the moon, and the sun on tides. As the known influence of these factors changed, the complex equations represented by the insides of the machine would give continual indications of how the tides were to rise and fall. The results were to come out in the form of a graph. Although the machine was not a complete success, it did mark a beginning.
15.Regardless of their direction or form, computer developments and uses of the future will depend upon the cleverness and skill of men. Men created computers, and men will continue to improve them.
16.Computers can work through a series of problems and make thousands of logical decisions without becoming tired. Computers can reach solutions to problems in a fraction of the time it takes men to do the job. Computers can replace men in dull, routine tasks, but they are not creative and cannot exercise value judgements. Computers have no originality； they work according to the instructions given to them. There are times when computers seem to operate like mechanical "brains"，but their achievements are not very great when compared to what the minds of men can do.
10.Which of the following paragraph divides the introductory part and the body of the article?