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
2023-07-04
74
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/2806810.html
相关试题推荐
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
There’snothingliketheinstinctiveroarofthecrowdwhenthousandsofpeo
随机试题
[originaltext]W:(12)Idon’tthinkitreallymatterswhatyoureducationalbackg
Feld,theshoemaker,wasannoyedthathishelper,Sobel,wassoinsensitive
《中华人民共和国合同法》规定的建设工程合同,是指以下哪几类合同?()Ⅰ.勘察
患者,男,50岁,便下脓血,里急后重,腹部灼痛,大便黏液恶臭;舌质红,苔黄腻津少
某期货公司是期货交易所的非结算会员,小王是该期货公司的客户。某日结算后,期货公司
以下不属于疠气的致病特点的是()A.发病急骤,病情重 B.高热持续不退
在我国历史上曾出现过多种宗教,最具影响的有( )。A.道教 B.佛教 C.
一、注意事项 1.本题本由给定材料与作答要求两部分构成。考试时限为
可以适用简易程序审理的案件是( )。A、起诉时被告下落不明的案件 B、宣告公民
下列选项中,适合用于一级公路基层的是()。A.水泥稳定级配碎石 B.二灰砂
最新回复
(
0
)