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
The human criterion for perfect vision is 20/20 for reading the standard lines on a Snellen eye chart without a hitch. The score
The human criterion for perfect vision is 20/20 for reading the standard lines on a Snellen eye chart without a hitch. The score
admin
2016-04-30
28
问题
The human criterion for perfect vision is 20/20 for reading the standard lines on a Snellen eye chart without a hitch. The score is determined by how well you read lines of letters of different sizes from 20 feet away. But being able to read the bottom line on the eye chart does not approximate perfection as far as other species are concerned. Most birds would consider us very visually handicapped. The hawk, for instance, has such sharp eyes that it can spot a dime on the sidewalk while perched on top of the Empire State Building. It can make fine visual distinctions because it is blessed with one million cones per square millimeter in its retina(视网膜). And in water, humans are farsighted, while the kingfisher, swooping down to spear fish, can see well in both the air and water because it is endowed with two foveae(凹窝)-areas of the eye, consisting mostly of cones, that provide visual distinctions. One fovea permits the bird, while in the air, to scan the water below with one eye at a time. This is called monocular vision. Once it hits the water, the other fovea joins in, allowing the kingfisher to focus both eyes, like binoculars, on its prey at the same time. A frog’s vision is distinguished by its ability to perceive things as a constant motion picture. Known as "bug detectors", a highly developed set of cells in a frog’s eyes responds mainly to moving objects. So, it is said that a frog sitting in a field of dead bugs wouldn’t see them as food and would starve.
The bee has a "compound" eye, which is used for navigation. It has 15,000 facets that divide what it sees into a pattern of dots, or mosaic. With this kind of vision, the bee sees the sun only as a single dot, a constant point of reference. Thus, the eye is a superb navigational instrument that constantly measures the angle of its line of flight in relation to the sun. A bee’s eye also gauges flight speed. And if that is not enough to leave our 20/20 "perfect vision" paling into insignificance, the bee is capable of seeing something we can’t—ultraviolet light. Thus, what humans consider to be "perfect vision" is in fact rather limited when we look at other species. However, there is still much to be said for the human eye. Of all the mammals, only humans and some primates can enjoy the pleasures of color vision.
What is the main idea of the passage?
选项
A、The differences between human eyes and other species’ eyes.
B、The advantages of other species’ eyes in comparison with human eyes.
C、The factors that make other species’ eyes better than human eyes.
D、The standard that determines the "perfect vision" of human eyes.
答案
A
解析
首段前3句通过描述人类测试视力的方法引出人类的视力不如其他物种这个话题,然后作者举了4个例子说明这个观点,而在第2段末句作者又指出人类视力在某一方面优于其他物种,由此可见,本文主要通过举例说明人类和其他物种在视力上的不同,由此可见,选项A概括了全文内容。第2段末句指出了人类视力也有优于其他物种视力的地方,选项B和C都强调其他物种的视力好,概括都不够全面;选项D只能概括文章首句的内容,其他的内容均未包括在内。
转载请注明原文地址:https://kaotiyun.com/show/DVG7777K
0
大学英语六级
相关试题推荐
Gender-NeutralLanguageA)Thepracticeofassigningmasculinegendertoneutraltermscomesfromthefactthateverylanguagere
Forthispart,youareallowed30minutestowriteanessayontheremark"Lieshaveshortlegs."Youcangiveexamplestoillus
Telecommunicationsisjustoneofthemeansbywhichpeoplecommunicateand,assuch,weneedtolookattelecommunicationsand
FilmSchoolsA)Filmschoolsandfilmdirectingschoolsprovideaspiringfilmstudentswithasolidunderstandingofthemanyfac
Awisemanoncesaidthattheonlythingnecessaryforthetriumphofevilisforgoodmentodonothing.So,asapoliceoffice
Awisemanoncesaidthattheonlythingnecessaryforthetriumphofevilisforgoodmentodonothing.So,asapoliceoffice
A、Sandyisworkingonherlabreports.B、Sandyisbusywithherengagement.C、Lisamightbeabletohelp.D、Lisaisalwaysonth
A、Trytosavemoneymonthbymonth.B、Trytoexerciseeachday.C、Trytobuysomenecessaryitems.D、Trytosticktoabudgetea
A、Parents’supportandloanforthestudents.B、Thedecliningopportunitiesforthequalifiedpeople.C、Thegrowingneedforhig
A、Printmaterialsforvisitors.B、Studyreferentialreports.C、AskSallytomakearrangements.D、Applytothechiefexecutive.B
随机试题
下列关于Word2010打印功能的说法中,不正确的是_____________。
A.小儿疳积发热B.胃肠湿热泻痢C.两者均是D.两者均非胡黄连的适应证是()
溃疡性结肠炎的发病部位不包括
胎盘的组成为
以下抗抑郁症药物的合理使用,叙述正确的有
根据所给韵经济业务编制会计分录。根据“工资结算汇总表”,本月发生基本生产车间生产工人工资56556元,车间管理人员工资9564元,行政管理部门人员工资54000元,福利部门人员工资4600元,专设销售机构人员工资19200元。编制分配工资费用的
袁雪芬、严凤英、红线女、叶盛兰分别是()的著名演员。
劳动者以辞职的形式解除劳动合同必须提前()天通知。
根据材料回答下列问题。人类对技术的乐观或悲观倾向由来已久,但普林斯顿大学历史学家爱德华.泰纳的说法可能会使你大吃一惊:技术不仅没有给人类缔造福祉,反而极大地报复了人类。泰纳写道:就在我们欢庆又把自然世界的混乱削减了几分之时,我们制造的新机器开始脱
阅读下列有关认识和实践关系的一组材料:材料1观念有三类:天赋的,外来的、虚构的。这是按照不同来源而做出的区分,虚构的观念是思想自己制造出来的,天赋的和外来的观念都是由思想以外的原因所造成的。因此上述观念可合并为两种:思想自己制造出来的和由外部
最新回复
(
0
)