专四专八好课
经典
专四备考规划
0元
专四水平测试
5分钟
英语专四全程班
特惠
专八备考规划
0元
专八水平测试
5分钟
英语专八全程班
特惠
零基础英语速升
考研好课特惠
介绍
资料下载
精选1000+
2018专八阅读理解练习题:视力研究
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 feetaway. 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 theair. 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 movingobjects. 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 hind 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 isnot 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.1. The Snellen eye chart measures one's eyesight by__________________.
A) the number of lines he reads
B) the distance he stands away from the chart
C) the speed at which he recognizes the letters
D) several integrative factors
2. How is hawk's eyesight better than ours?
A) It can identify small items more quickly than we do.
B) It can see ai a longer distance than we do.
C) It has more cones in che retina than we do.
D) It has bigger eyes than we do.
3. Monocular vision enables the kingfisher to__________________.
A) avoid farsightedness
B) be able to see underwater
C) move one eye at a time
D) focus its eyes on the prey
4. A bee finds its direction by_______________________.
A) dividing what it sees into thousands of dots
B) constantly gauging its flying speed
C) using the sun as a constant point of reference
D) measuring the angle of the sun
5. What is the main idea of the passage'?
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 me "perfect vision” of human eyes.
专四专八精选好课 暖心助学
新东方好老师 手把手带学
资料下载
专八听力训练:时政短语热点【word版】
发布时间:2020-04-01关注新东方在线服务号
回复【专八听力】获取
专八翻译模拟练习题总结
发布时间:2020-04-01关注新东方在线服务号
回复【专八翻译】获取
专四专八写作必备高级词汇
发布时间:2020-04-01关注新东方在线服务号
回复【专八作文】获取
专四听力听写练习50篇文本文档
发布时间:2020-04-01关注新东方在线服务号
回复【专四听力】获取
2021专四写作高级范文15篇集锦
发布时间:2020-04-01关注新东方在线服务号
回复【专四写作】获取
专八基础词汇积累完整版(169页全)
发布时间:2019-12-26关注新东方在线服务号
回复【专八词汇】获取
英语专业四级词汇PDF电子版
发布时间:2019-12-26关注新东方在线服务号
回复【专四词汇】获取
近十年专八真题答案及听力原文
发布时间:2019-12-26关注新东方在线服务号
回复【专八真题】获取
近十年专四真题答案及听力原文
发布时间:2019-12-26关注新东方在线服务号
回复【专四真题】获取
关注新东方在线服务号
关注新东方在线服务号,
免费获取专四专八必看干货资料
推荐阅读
更多>>新东方在线专四专八频道给大家整理的相关内容,希望能够对大家的专四专八考试备考有所帮助,更多有关专四专八的备考内容,欢迎随时关注
来源 : 网络 2024-02-17 18:40:00 关键字 : 英语专八
新东方在线专四专八频道给大家整理的相关内容,希望能够对大家的专四专八考试备考有所帮助,更多有关专四专八的备考内容,欢迎随时关注
来源 : 网络 2024-02-16 18:40:00 关键字 : 英语专八
新东方在线专四专八频道给大家整理的相关内容,希望能够对大家的专四专八考试备考有所帮助,更多有关专四专八的备考内容,欢迎随时关注
来源 : 网络 2024-02-01 18:40:13 关键字 : 英语专八
新东方在线专四专八频道给大家整理的相关内容,希望能够对大家的专四专八考试备考有所帮助,更多有关专四专八的备考内容,欢迎随时关注
来源 : 网络 2024-02-01 18:39:43 关键字 : 英语专八
新东方在线专四专八频道给大家整理的相关内容,希望能够对大家的专四专八考试备考有所帮助,更多有关专四专八的备考内容,欢迎随时关注
来源 : 网络 2024-02-15 18:39:00 关键字 : 英语专八
精彩课程推荐
更多>>直录播结合,知识点精讲,好老师带学,带你稳稳走好备考路
火热报名
直录播精讲互动二合一,新东方好老师全程带学不迷茫!
火热报名
资料下载
更多>>关注新东方在线服务号
回复【专八听力】获取
关注新东方在线服务号
回复【专八翻译】获取
关注新东方在线服务号
回复【专八作文】获取
关注新东方在线服务号
回复【专四听力】获取
关注新东方在线服务号
回复【专四写作】获取
关注新东方在线服务号
回复【专八词汇】获取
关注新东方在线服务号
回复【专四词汇】获取
关注新东方在线服务号
回复【专八真题】获取
关注新东方在线服务号
回复【专四真题】获取
阅读排行榜
相关内容