[单项选择]Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bones or horns, metal knives and more recently, rubber and plastic. In the 1960s a new tool was developed, one which was, first of all, to be of great practical use to the armed forces and industry, but which was also to revolutionize the art and science of surgery.
The tool is the laser and it is being used by more and more surgeons all over the world. As we all know, light is hot, and any source of light will give warmth. But light is usually spread out over a wide area. The light in a laser beam, however, is concentrated. This means that a light with no more power than that produced by an ordinary electric light bulb becomes intensely strong as it is concentrated to a pinpoint-sized beam.
Experiments with these pinpoint beams showed researchers that different energy sources produce beams that have a particular effect on certain living cells. It is now possible for eye surgeons to o
A. leave their patients with negative effects
B. can treat only human eye diseases
C. do little damage to their patients
D. make their patients need a long time to recover

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Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bone or horn, metal knives and more recently, rubber and plastic. And that was where we stuck, in surgical instrument terms, for many years. In the 1960s a new tool was developed, one which was, first of all, to be of great practical use to the armed forces and industry, but which was also, in time, to revolutionize the art and science of surgery.
The tool is the laser and it is being used by more and more surgeons all over the world, for a very large number of different complaints. The word laser means: Light Amplification by Stimulated Emission of Light. As we all know, light is hot; any source of light ——from the sun itself down to a humble match burning ——will give warmth. But light is usually spread out over a wide area. The light in a laser beam, however, is concentrated. This means that a light with no more power than that produced by an ordinary ele
A. fashionable
B. extraordinary
C. special
D. basic

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