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
Many people believe the glare from snow causes snow blindness. Yet, dark glasses or not they find themselves suffering from head
Many people believe the glare from snow causes snow blindness. Yet, dark glasses or not they find themselves suffering from head
admin
2011-06-29
65
问题
Many people believe the glare from snow causes snow blindness. Yet, dark glasses or not they find themselves suffering from headaches and watering eyes, and even snowblindness, when exposed to several hours of "snow light".
The United States Army has now determined that the glare from snow does not cause snow-blindness in troops in a snow-covered country. Rather, a man’s eyes frequently find nothing to focus on in a broad expanse of a snow-covered area So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at. Finding nothing, hour after hour, the eyes never stop searching and the eyeballs become sore and the eye muscle aches. Nature balances this annoyance by producing more and more liquid which covers the eyeballs. The liquid covers the eyeballs in increasing quantity until vision blurs. And the result is total, even though temporary, snowblindness.
Experiments led the Army to a simple method of overcoming this problem. Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape. Even the scouts themselves throw lightweight, dark-colored objects ahead on which they too can focus. The men following can then see something. Their gaze is arrested. Their eyes focus on a bush and having found something to see, stop searching through the snow-blanketed landscape. By focusing their attention on one object at a time, the man can cross the snow without becoming hopelessly snowblind or lost. In this way the problem of crossing a solid white area is overcome.
The eyeballs become sore and the eye muscles ache because______.
选项
A、tears cover the eyeballs
B、the eyes are annoyed by blinding sunlight
C、the eyes are annoyed by blinding snow
D、there is nothing to focus on
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/iv6O777K
0
考博英语
相关试题推荐
Youcancomewithmetothemuseumthisafternoon______youdon’tmindwalkingforhaftanhour.
Perhapsallcriminalsshouldberequiredtocarrycardswhichread:Fragile;HandlewithCare.Itwillneverso,thesedaystog
IncomeinequalityintheUnitedStatesremainedrelativelystableforaperiodofnearlyfortyyears.Beginninginthe1970’s,h
Itisnotunusualforchiefexecutivestocollectmillionsofdollarsayearinpay,stockoptions,andbonuses.Inthelastfif
Superstitionisadifficultquestion.WecannotquitesaythatsuperstitioninBritainisdead.Itshistoryisboth【76】longand
Superstitionisadifficultquestion.WecannotquitesaythatsuperstitioninBritainisdead.Itshistoryisboth【76】longand
DearSirs,IamwritingtoyourofficetoattempttodeterminewhyIhaveencouragedsomanyobstaclestoreceivingmyproper
TheAerospaceBicycleThatFelltoEarth(1)AradicalnewbicyclehaditsfirstpublicshowingattheNationalBritishCycli
一些法官已允许医院让没有希望康复的病人停用维持生命的设备。但是,我说这是残忍的谋杀。我们要么现在就中止这种惯常作法,要么就应该尽快为老人、体弱者和其他被认为是负担的人制定安乐死计划。我们应该让病情自然地发展而不应该停用维持生命的设备。
随机试题
首先提出群体三要素的社会心理学家是()。
老年性阴道炎的基本病因是
某患者的半口义齿蜡型,烫盒后打开型盒时发现,塑料牙未能翻至上半盒内,冲蜡后复位不牢,其原因是
螺旋霉素属()。
某工业生产企业,以产量表示的盈亏平衡点是300台。预计今年的固定成本将增加20%,其他条件不变化,则盈亏平衡点将变为( )。
某烟丝加工厂为增值税一般纳税人,2018年7月接受某烟厂委托加工烟丝,烟丝加工厂自行提供烟叶的成本为32000元,代垫辅助材料2000元,加工费支出5000元;烟丝加工厂上月留抵增值税为3400元。下列说法正确的是()(烟丝消费税税率为30%,成本
物流作业信息系统是按照()形成的信息管理与软件控制。
系统测试的原则包括()。
根据下面材料回答下列小题。2006年1-10月中央项目与地方项目固定资产投资的比例为()。
当数据分组从低层向高层传送时,分组的头要被(28)。
最新回复
(
0
)