题目内容
（请给出正确答案）
提问人：网友xj4150
发布时间：2022-01-07
[主观题]
Once external surgery is started, the surgeon uses smaller, more delicate devices.
简答题官方参考答案
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查看官方参考答案
Thousands of years ago man used handy rocks for his surgical operations．Later he used sharpbones or horns, metal knives and more recently, rubber and plastic．In the 1960s a new tool wasdeveloped, one which was, first of all, to be of great practical use to the armed forces and indus-try, 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 weall know, light is hot, and any source of light will give warmth．But light is usually spread outover a wide area．The light in a laser beam, however, is concentrated．This means that a light withno more power than that produced by an ordinary electric light bulb becomes intensely strong as itis concentrated to a pinpoint-sized beam．
Experiments with these pinpoint beams showed researchers that different energy sources pro-duce beams that have a particular effect on certain living cells．It is now possible for eye surgeonsto operate on the back of human eye without harming the front of the eye, simply by passing a laserbeam right through the eye-ball．Operations which once left patients exhausted and in need of longperiod of recovery time now leave them feeling relaxed and comfortable．
The rapid development of laser techniques in the past ten years has made it clear that the futureis likely to be very exciting．Perhaps some cancers will be treated with laser in a way that makessurgery not only safer but also more effective．
Which of the following would be appropriate to describe the instruments of surgical opera-tions up until 1960s? 查看材料
A.Traditional．
B.Complicated．
C.Remarkable．
D.Revolutionary．
