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It has been necessary to refer repeatedly to the effects of the two world wars in promoting all kinds of innovation. It should be (21) also that technological innovations have (22) the character of war itself by (23) of new mechanical and chemical devices. One weapon developed during World War Ⅱ (24) a special mention. The (25) of rocket propulsion was well known earlier, and Us possibilities as a (26) of achieving speeds sufficient to escape from the Earth’ s gravitational pull had been (27) by the Russian and the American scientists. The latter built experimental liquid-fuelled rockets in 1926. (28) , a group of German and Romanian pioneers was working (29) the same lines, and in the 1930s, it was tins team that developed a rocket (30) of delivering a warhead hundreds miles away. Reaching a height of over 100 miles, the V-2 rocket (31) the beginning of the Space Age, and members of its design team were (32) in both the Soviet and United States space programs after the war. Technology had a tremendous social (33) in the period 1900-45. The automobile and electric power, (34) , radically changed both the scale and the quality of 20th-century life, (35) a process of rapid urbanization and a virtual revolution (36) living through mass production of household goods and (37) . The rapid development of the airplane, the cinema, and radio made the world seem suddenly smaller and more (38) . The development of many products of the chemical industry further transformed the life of most people. In the years (39) 1945 the constructive and creative opportunities of modern technology could be (40) , although the process has not been without its problems.
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It has been necessary to refer repeatedly to the effects of the two world wars in promoting all kinds of innovation. It should be (21) also that technological innovations have (22) the character of war itself by (23) of new mechanical and chemical devices. One weapon developed during World War Ⅱ (24) a special mention. The (25) of rocket propulsion was well known earlier, and Us possibilities as a (26) of achieving speeds sufficient to escape from the Earth’ s gravitational pull had been (27) by the Russian and the American scientists. The latter built experimental liquid-fuelled rockets in 1926. (28) , a group of German and Romanian pioneers was working (29) the same lines, and in the 1930s, it was tins team that developed a rocket (30) of delivering a warhead hundreds miles away. Reaching a height of over 100 miles, the V-2 rocket (31) the beginning of the Space Age, and members of its design team were (32) in both the Soviet and United States space programs after the war. Technology had a tremendous social (33) in the period 1900-45. The automobile and electric power, (34) , radically changed both the scale and the quality of 20th-century life, (35) a process of rapid urbanization and a virtual revolution (36) living through mass production of household goods and (37) . The rapid development of the airplane, the cinema, and radio made the world seem suddenly smaller and more (38) . The development of many products of the chemical industry further transformed the life of most people. In the years (39) 1945 the constructive and creative opportunities of modern technology could be (40) , although the process has not been without its problems.
Passage 4 Surgeons will soon be able to enter the eye to carry out operations--at least in a virtual sense. Techniques derived from virtual reality--the computer system that immerses operations in an artificial computer-generated world--will allow surgeons to feel as if he could see the inside of the eye during an operation, creating the illusion that they are actually there. Researchers at the Biorobotics Laboratory of McGill University in Montreal are building a robot, known as Micro Surgery robot - 1 (MSR - I for short), that will perform delicate operations under the control of a human surgeon. The robot is specifically designed for performing eye surgery but could have other applications, such as the removal of brain tumors. The system could also be used to allow surgeons and their students to practise simulated surgery that feel like the real thing-without the real consequences for the patients. During the operations, the surgeon manipulates a set of control known as the master. These are connected through a high-performance computer to the robot. Both the master and the robot have two limbs, When the surgeon moves the masters’ limbs, the robots limbs move in exactly the same way, except that the movements can be scaled down as much as a thousand times. This will eliminate hand tremor and poor accuracy and thus reduce the damage to the eye that can occur with present microsurgery techniques. Each of the robots limbs has a minimum movement of one micrometer--more than one hundred times the precision of the human hand. The computer also creates a three-dimensional robot’ s eye view of the inside of the eye that the surgeon can see by wearing a virtual reality helmet that has a small lens in front of each eye. To provide the surgeon with such a realistic experience, MSR-I must be able to move rapidly, but this requires extremely fast computing. To handle the computational demands of instant interaction, the McGill team is constructing its own parallel-processing computer. It is also studying areas such as muscle mechanism, artificial intelligence and optics, and has a already built another micro robot MR-I, capable of manipulating a single living cell. Although commercial applications of the new system are not expected for several years, its basic mechanical components will be ready for testing in a few months, "The day when micro-robots will be able to perform surgery without human intervention is many years away," says Hunter, "in the meantime, a system such as MRS-I is a necessary precursor." What is the chief advantage of the virtual reality techniques when used in microsurgery
太阳能和化学能通过______，源源不断地输入到生态系统，成为消费者和还原者的唯一能源。
Passage 3 Many of the most damaging and life-threatening types of weather--torrential rains, severe thunderstorms, and tornadoes--begin quickly, strike suddenly, and dissipate rapidly, devastating small regions while leaving neighboring areas untouched. One such event, a tornado, struck the northeastern section of Edmonton, Alberta, in July 1987. Total damages from the tornado exceeded ＄ 250 million, the highest ever for any Canadian storm. Conventional computer models of the atmosphere have limited value in predicting short-lived local storms like the Edmonton tornado, because the available weather data are generally not detailed enough to allow computers to discern the subtle atmospheric changes that precede these storms. In most nations, for example, weather-balloon observations are taken just once every twelve hours at locations typically separated by hundreds of miles. With such limited data, conventional forecasting models do a much better job predicting general weather conditions over larger regions than they do forecasting specific local events. Until recently, the observation--intensive approach needed for accurate, very short-range forecasts, or "Nowcasts", was not feasible. The cost of equipping and operating many thousands of conventional weather stations was prohibitively high, and the difficulties involved in rapidly collecting and processing the raw weather data from such a network were insurmountable. Fortunately, scientific and technological advances have overcome most of these problems. Radar systems, automated weather instruments, and satellites are all capable of making detailed, nearly continuous observation over large regions at a relatively low cost. Communications satellites can transmit data around the world cheaply and instantaneously, and modern computers can quickly compile and analyzing this large volume of weather information. Meteorologists and computer scientists now work together to design computer programs and video equipment capable of transforming raw weather data into words, symbols, and vivid graphic displays that forecasters can interpret easily and quickly. As meteorologists have begun using these new technologies in weather forecasting offices, Nowcasting is becoming a reality. With Nowcasting, it first became possible to provide information about ______ .
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