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
13
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
转载请注明原文地址:https://tihaiku.com/zcyy/3425118.html
相关试题推荐
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
[originaltext]Jointhethousandsofprofessionalsandinternationaltravele
[originaltext]Jointhethousandsofprofessionalsandinternationaltravele
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thethousandsofpeopleforcedtoabandontheirhomesinrecentweekstoflo
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Lat
随机试题
下列属于肾炎综合征的是()。A.蛋白尿 B.血尿 C.高血压 D.肾功能
已知f(x)和g(x)在x=0点的某邻域内连续,且x→0时f(x)是g(x)的高
目前国内最常见的细菌性痢疾病原菌是:A.福氏痢疾杆菌 B.宋内痢疾杆菌 C.
治理地表水和地下水的原则:防止地表水流边坡表面裂隙中;采用疏干措施降低潜在破坏面
A.期门 B.大敦 C.隐白 D.章门 E.曲泉常用于治疗阴痒、遗精、小
高压熔断器更换应使用参数相同的熔断器。
教育行政部门取缔了一批违反国家规定私自招收未成年学生的私立学校,教育行政部门这一
我国政府预算改革的目标是要建立全口径预算体系,包括()。A.一般公共预算 B
收取公用事业费事宜采取()结算方式。 A.委托付款B.托收承付C.商业汇
患者,男,25岁,双下肢乏力伴尿潴留10天就诊.查体:双下肢肌力Ⅲ级,脐以下感觉
最新回复
(
0
)