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
2023-07-02
59
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:https://tihaiku.com/zcyy/2800617.html
相关试题推荐
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
随机试题
我们也不应该忘记,广告给我们的钱袋作出了积极的贡献。没有这笔收入来源,报纸、商业电台和电视公司就不能生存。我们花很少的钱就能买到一份日报,或者能够欣赏如此
2009wastheworstyearfortherecordlabelsinadecade.【C1】______was2008
Whathappenswhenonestudenthurtsanother’sindividualrights?Standardsa
A.-896.3kJ·mol-1 B.+937.4kJ·mol-1 C.-3
下列不属于毛果芸香碱的药理作用的是A.眼内压减低 B.胃肠道平滑肌收缩 C.
现金的( )随现金持有量的增加而下降,随现金持有量的减少而上升。A.重置成本
血栓前状态不能反映A.血管内皮细胞受损B.血小板和白细胞功能亢进C.血液黏度增加
个人投资者作为询价对象应当具备的条件包括()。A:3年以上投资经验B:5年以上
政府对价格的管制,主要是为了解决()等问题。 A.行政垄断B.自然垄断
电话快报的内容包括()。A.事故发生单位的名称、地址、性质 B.事故的简要经
最新回复
(
0
)