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
2016-12-05
68
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/19rd777K
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
SpringhascometoPortlandatlast.Theskyisblue.Birds【M1】______aresingingonthetrees,flowersareblooming,and
Thelittlegirlwhogotlostdecidedtoremain______shewasandwaitforhermother.
OneafternoonIwassittingatmyfavoritetableinarestaurant,waitingforthefoodIhadordered.SuddenlyI【36】thatamansit
OneafternoonIwassittingatmyfavoritetableinarestaurant,waitingforthefoodIhadordered.SuddenlyI【36】thatamansit
TheInternetisawayoflifeforUScollegestudents.ArecentsurveybyHarrisInteractiveand360youthfoundthat93percen
Cars!!!Holidays!Thousandsofprizes!Hurry!FREEwitheverypacketofSPLASH!Yourpersonalluckynumber!Willbeamon
Henrywasdeportedforhavinganexpiredvisa.He______hisvisarenewed.
根据下列图画所示,请用英语将所发生的故事写出来,词数100个左右。
InAmerica,drivers’educationispartoftheregularhighschoolcurriculum.Everystudentinhisorhersecondyearofhighsc
Thousandsofyearsagomanusedhandyrocksforhissurgicaloperations.Laterheusedsharpbonesorhorns,metalknivesandmo
随机试题
目前,对外汇的限制主要在()
下列疾病中,可产生杵状指的是【】
患者,女,37岁,停经59天,妊娠反应10余日,今日突然阴道出血就诊,妇科检查发现子宫孕3个月大小,子宫两侧扩及4cm×3cm×5cm的囊性包块,宫颈口有少量血液流出。考虑可能为
不属于颗粒剂质量检查项目的是
土的CBR值指试料贯入量达2.5mm时,单位压力对哪种压入相同贯入量时荷载强度的比值?()
下列财务指标中,可以用来反映公司资本结构的有()。
公开发行公司债券,股份有限公司的净资产应当不低于人民币()。
在窗体上画一个名称为Command1的命令按钮,然后编写如下通用过程和命令按钮的事件过程;PrivateFunctionfun(ByValmAsInteger)IfmMod2=0Thenf
以下叙述错误的是()。
给英语老师发一封电子邮件,并将考生文件夹下的文本文件homework.txt作为附件一起发送。具体要求如下:【收件人】wanglijuan@cuc.edu.cn【主题】课后作业【内容】王老师,您好!我的作业已经完成,请批阅。具体见附件。
最新回复
(
0
)