首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bones or horns, metal knives and mo
Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bones or horns, metal knives and mo
admin
2014-05-25
62
问题
Thousands of years ago man used handy rocks for his surgical operations. Later he used sharp bones or horns, metal knives and more recently, rubber and plastic. 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 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. As we all know, light is hot, and any source of light 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. Operations which once left patients exhausted and in need of long period of recovery time now leave them feeling relaxed and comfortable.
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.
The reason why the laser beam is very strong is that______.
选项
A、it is artificially illuminated
B、it is made up of a concentrated beam of light
C、it sends out heat in all directions
D、its heat is increased by the heat of the sun
答案
B
解析
事实细节题。题干的意思是“为什么激光束的能量比较强?”根据原文第二段最后一句可知“能量被集中到一起而变得强大”。故答案为B。
转载请注明原文地址:https://kaotiyun.com/show/HBud777K
本试题收录于:
公共英语二级笔试题库公共英语(PETS)分类
0
公共英语二级笔试
公共英语(PETS)
相关试题推荐
--HowmuchwillIpayforthedinner?---twentydollarswill______allyouwanttohave.
Howwouldyouunderstand"tablemanners"(Line1,Para.2)?Guestswhoareunfamiliarwithtablemannersoftenappearatdinner
ChristmasEvearrivesatmyhouseeachyear.Thecenterofthecelebrationisdinner.Mymotherspendsdayspreparingarichvar
Thebesttitleforthetextwouldbe______.OneimportantdifferencebetweenaninfotainmentandanordinaryTVnewsprogrami
Theycalled______thematchbecauseofrain.
Cars!!!Holidays!Thousandsofprizes!Hurry!FREEwitheverypacketofSPLASH!Yourpersonalluckynumber!Willbeamon
Cars!!!Holidays!Thousandsofprizes!Hurry!FREEwitheverypacketofSPLASH!Yourpersonalluckynumber!Willbeamon
Cars!!!Holidays!Thousandsofprizes!Hurry!FREEwitheverypacketofSPLASH!Yourpersonalluckynumber!Willbeamon
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Laterheusedsharpbonesorhorns,metalknivesandmo
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Laterheusedsharpbonesorhorns,metalknivesandmo
随机试题
A、烈日暴晒或强烈热辐射作用于头部,引起脑组织充血、水肿B、大量出汗后口渴,而饮水过多,引起脑组织水肿C、大量出汗后口渴,而饮水过多,盐分补充不足,感觉四肢无力D、大量出汗导致失水、失钠,血容量不足而致周围循环衰竭E、高温下大量出汗仍不足以散热或体
《脉经》的作者是《小儿药证直诀》的作者是
关于推荐“互联网+”便捷交通的说法,错误的是()。
按照波特的基本竞争战略模型,企业实施差异化竞争策略的途径有()。Ⅰ.产品差异化Ⅱ.服务差异化Ⅲ.形象差异化Ⅳ.市场差异化
某教育发展有限公司(具有培训资质,同时具有一般纳税人资格),主要从事财经类考试培训,广告发布、图书销售、财税类咨询服务。该单位各个项目分开核算。2012年10月发生的业务如下:(1)购进纸张和办公用品,取得增值税专用发票,注明价款85万元;购进
单位可以开立以下选项中哪些用途的专用存款账户?()
皮尔是个非常有远见的英国资本家。他经过认真细致的考察,发现新荷兰(澳大利亚)的斯旺河物产富饶,所以他预料到那里投资一定会为他带来丰厚的利润。于是,他把价值5万英镑的生活资料和生产资料从英国带到斯旺河去,并同时带去了3000名男工、女工和童工,企图在那里赚取
老龄事业
The"YouthEmancipation"programmeaimsathelpingyoungpeople______.Itcanbeinferredfromparagraph5thatfamilytiesare
AFewAspectsofAmericanLifeTravelA)It’ssummertime.FormanyAmericans,thisistheseasontotravel.Why?Becauseschool
最新回复
(
0
)