高考英语阅读训练（015）
The United States is not the only country affected by the“computer revolution”,All the major countries of the world have computers ,and the developing countries have also realized that computers play a big part in their economic development.
Usually what one sees is a machine that looks like a typewriter ;it is called a computer terminal（终端）But computers are also used in unseen ways For example they determine how much tine there should be between traffic signals to prevent traffic problems and to keep millions of cars moving in an orderly flow When you buy a car ,a factory process （过程）that is controlled by a computer enables you to obtain a car with your own choice of colours and special features （特征）in just a few weeks’ time In medical laboratories ,com-puters have reduced the mistakes in testing ,and they have saved doctors’ countless hours of work Before long ,medical histories of all Americans will be kept in computer “banks”.If a person becomes ill far from his home ,local doctors will be able to get his medical record immediately ,In science the computer has performed in minutes experiments which would have required thousands of hours of work by human hands and minds.
Most experts agree that computers are necessary to solve the problems of increasing population ,city living ,and public affairs Without computers, the jobs of solving these problems would require millions of workers to do tons of paperwork Before any computer can work on any problem, it must be told what to do Someone must program the computer ,step―by―step. At first this was done by having the programmer write out his instructions in the form of numbers which would be“understood”by the machine ,Within a short time, attempts were made to perform a system that would enable humans to communicate programmer could use words that had meanings for