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Dạng bài Đọc hiểu lớp 12

Why do surgeons prefer lasers to surgical knives?

Read the following passage and mark the letter A, B, C. or D se year answer sheet to indicate the correct answer to each of the question.

In the early years after the invention of lasers, scientists called thirst a solution looking for a problem." It was obvious that lasers were vex! special, but it took scientists a while to find practical applications for them. Over time, hundreds of uses have been found for lasers in many areas of science and technology. They are used in the newest telecommunication systems, in computer printers, and in compact disc players. They are also used in show business to create special lighting effects. But where lasers have made the most difference is undoubtedly in the world of medicine, where they can be used for many tasks that require fine precision.

First, doctors can use lasers as cutting tools. Surgeons prefer lasers to surgical knives for certain operations because laser beams can be made much narrower than a knife blade. Also, with lasers, doctors can work more quickly than with metal tools, and so there is less risk of infection. Furthermore, a laser beam produces heat, which helps to close off the skin or tissue being cut into and reduces bleeding. Thus, lasers have proved extremely useful in the fine surgery required to reconstruct veins and arteries. They are also used in surgery to remove certain kinds of brain or liver cancers. Doctors are experimenting with ways to find cancer in various parts of the body through the use of a colored liquid that colors only the cancerous areas. Then they can use lasers designed for that color to find the cancer and burn it away. This removes the disease from the body but damages nothing else.

Lasers have also dramatically changed the work of eye doctors. Poor vision is one of the most common medical problems in the world, and until recently the only way to correct it was with eyeglasses or contact lenses. Now many vision problems can be corrected permanently with laser surgery. This surgery has made an enormous difference for people who were practically blind without their glasses or contact lenses. After a lifetime of worrying about breaking or losing their glasses or lenses, they can see normally without them. For eye surgery, doctors need to be extremely precise and extremely quick. A • They use what is known as a cool laser, which produces beams that can cut out 39 millionths of an inch of tissue in 12 billionths of a second. In other words, this kind of laser is so precise it could cut into a strand of hair without cutting all the way through. B• In vision surgery, these lasers are used on a part of the eye called the cornea, which is the transparent covering on the outside. When the cornea is not perfectly round, we cannot see clearly. C • The process takes only a few minutes and because the laser is cool, there is little pain D • 

Câu 15845: Why do surgeons prefer lasers to surgical knives?

A. Surgical knives are too sharp.

B. Surgical knives are not big enough

C. Lasers provide fine precisions.

D. Laser beams are lighter. 

Câu hỏi : 15845
  • Đáp án : C
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