首页
登录
职称英语
Thousands of years ago man used handy rocks for his surgical operations. Lat
Thousands of years ago man used handy rocks for his surgical operations. Lat
游客
2024-02-05
24
管理
问题
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 radiation. 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 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 operate on the back of human eye without harming the front of the eye, simply by passing a laser beam right through the eye-ball. No knives, no stitches, no unwanted damage — a true surgical wonder. Operations which once left patients exhausted and in need of long period of recovery time now leave them feeling relaxed and comfortable. So much more difficult operations can now be tried.
The rapid development of laser techniques in the past ten years has made it clear that the future is likely to be very exciting. Perhaps some cancers will be treated with laser in a way that makes surgery not only safer but also more effective. Altogether, tomorrow may see more and more information coming to light on the diseases which can be treated medically. [br] What is the reason mentioned in the passage that the laser beam is so strong?
选项
A、It sends out light to cover a wide area.
B、It has many sources of light.
C、It is a highly concentrated beam of light.
D、The source of its heat comes from the sun.
答案
C
解析
细节题。第二段最后一句提到,当一束普通的光聚集成针尖大小时,它的能量会非常强。故答案为C。
转载请注明原文地址:http://tihaiku.com/zcyy/3423076.html
相关试题推荐
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
随机试题
TaskOneForquestions13—17,matchtheextractswiththejobs,listedA—H.Fo
Accordingtothearticle,agoodstudentincollegemust______.[br]Dailyatte
There’sNoPlaceLikeHome[A]Onalmostanynightofthe
不属于金融服务类中间业务的是()。A.结算业务 B.代理业务
图示单元体,法线与x轴夹角a=45°的斜截面上切应力τ是:
细粉是指A.能全部通过二号筛,但混有能通过四号筛不超过40%的粉末 B.能全部
关于站用交流电源系统运行规定说法,下列不正确的是()(A)两路不同站用变电源供电
(2019年真题)借助载体帮助,消耗能量,从膜的低浓度一侧向高浓度一侧转运药物的
下列各项中,属于注册会计师项目组内部讨论的主要内容的有()。A.管理层是否
某开发商与施工企业签订合同,约定双方就合同履行发生争议,提交北京市A仲裁委员会进
最新回复
(
0
)