點擊查看：2018年6月大學英語六級閱讀100篇

　　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(視網膜). 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.(凹窩)-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.

　　答案：

　　1.Snellen視力表是通過什么來測量一個人的視力的?

　　A)受試者能夠看清的行數。

　　B)受試者離視力表距離的遠近。

　　C)受試者識別字母的速度。

　　D)幾個綜合的因素。

　　[A]首段第2句中的lines of letters和第3句中的bottom line表明視力的好壞是依靠看到視力表的行數來決定的，選項A為本題答案。首段第2句表明測驗視力時距離是預先設定的，選項B不正確;選項C屬于無中生有，原文并未提及該內容;文中只提到視力的好壞取次于能看到多少行字母這一因索，并沒有提到其他因素，故D項錯誤。

　　2.鷹眼比人眼好在什么地方?

　　A)鷹眼可以比人更快地識別小的物體。

　　B)鷹眼可以從更遠的距離來看清物體。

　　C)鷹眼視網膜的圓錐細胞比人眼多。

　　D)鷹眼比人眼大。

　　[B]首段笫5句中的while perched on top of the Empire State Building表明本句強調的是鷹能看到距離很遠的物件，由此可見，選項B為本題答案。從首段第5句中的dime一詞可以推斷鷹可以看到很小的物件，但原文并沒有暗示它辨認物件的速度，更沒有在這方面與人眼作比較，因此選項A不正確;首段第6句只是指出鷹眼的視網膜每平方毫米有100萬個圓錐細胞，但并沒有對比人眼和鷹眼所具有的圓錐細胞的總數，因此選項C不正確;原文并來提及與選項D有關的內容。

　　3.單眼視力讓翠鳥能夠_________________。

　　A)避免遠視

　　B)看到水底的東西

　　C)一次轉動一個眼睛

　　D)讓眼睛聚焦在獵物上

　　[C]首段第9句中的This表明前一句(即第8句)就是monocular vision的定義，很明顯，選項C為本題答案。首段第7句表明翠鳥在水里能看得清楚，不會像人類那樣遠視，是因為它眼睛里有兩個凹窩區域，并非因為它具有單眼視覺，因此選項A和B都不正確;根據該段第10句可知兩個凹窩區域同時發揮作用才能使翠鳥把目光聚焦到獵物身上，因此選項D不正確。

　　4.蜜蜂是通過什么來辨別方向的?

　　A)將它看見的東西分成幾千個點。

　　B)不斷地測量自己的飛行速度。

　　C)始終將太陽視作一個參照點。

　　D)測量太陽的角度。

　　[C]第2段第3，4句描述了蜜蜂利用太陽導航的機制，將選項與這些細節對照可以知道選項C為正確的說法。選項A是蜜蜂的成像機制，雖然眼睛必然與導航有關，但單靠成像并不能起到導航的作用，因此選項A不是蜜蜂尋找方向的方法：選項B中的gauging its flying speed也跟蜜蜂尋找方向無關：第2段第4句表明蜜蜂測量的是飛行路線和太陽的夾角，而不是測量太陽的角度，因此選項D不正確。

　　5.本文的主旨是什么?

　　A)人類的跟晴和其他物種的眼睛的不同之處。

　　B)相較于人的眼睛，其他物種的眼睛的優勢。

　　C)其他物種的眼睛優于人類的眼睛有哪一些要素。

　　D)決定人類眼睛的“完美視力”的標準。

　　[A]首段前3句通過描述人類測試視力的方法引出人類的視力不如其他物種這個話題，然后作者舉了4個例予說明這個觀點，而在第2段末句作者又指出人類視力在某一方面優于其他物種，由此可見，本文主要通過舉例說明人類和其他物種在視力上的不同，由此可見，選項A概括了全文內容。第2段末句指出了人類視力也有優于其他物種視力的地方，選項B和C都強調其他物種的視力好，概括都不夠全面;選項D只能概括文章首句的內容，其他的內容均未包括在內。

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