招生考试网
学历| 高考 美术高考 考研 自考 成考 专升本 中考 会考 外语| 四六级 职称英语 商务英语 公共英语 日语能力 翻译资格 JTEST
资格| 公务员 报关员 银行从业 司法 导游 教师资格 报关 财会| 会计证 经济师 会计职称 注册会计 税务师 资产评估 审计师
工程| 一建 二建 造价师 造价员 咨询师 监理师 安全师 医学| 卫生资格 执业医师 执业药师 执业护士 | 教案 论文 文档
IT类| 计算机等级 计算机软考 职称计算机 高校计算机 推荐-国家公务员 事业单位招聘 军校国防生 自主招生 艺术特长生 招飞
 3773考试网 - 大学英语四六级 - 英语六级 - 正文

2015年12月英语六级阅读标准练习6

来源:2exam.com 2015-8-30 13:41:57

You stare at waterfall for a minute or two, and then shift your gaze to its surroundings. What you now see appears to drift upward.

These optical illusions occur because the brain is constantly matching its model of reality to signals from the body’s sensors and interpreting what must be happening—that your brain must have moved, not the other; that downward motions is now normal, so a change from it must now be perceived as upward motion.

The sensors that make this magic are of two kinds. Each eye contains about 120 million rods, which provide somewhat blurry black and white vision. These are the windows of night vision; once adapted to the dark, they can detect a candle burning ten miles away.

Color vision in each eye comes from six to seven million structures called cones. Under ideal conditions, every cone can “see” the entire rainbow spectrum of visible colors, but one type of cone is most sensitive to red, another to green, a third to blue.

Rods and cones send their messages pulsing an average 20 to 25 times per second along the optic nerve. We see an image for a fraction of a second longer than it actually appears. In movies, reels of still photographs are projected onto screens at 24 frames per second, tricking our eyes into seeing a continuous moving picture.

Like apparent motion, color vision is also subject to unusual effects. When day gives way to night, twilight brings what the poet T.S. Eliot called “the violet hour.” A light levels fall, the rods become progressively less responsive. Rods are most sensitive to the shorter wavelengths of blue and green, and they impart a strange vividness to the garden’s blue flowers.

However, look at a white shirt during the reddish light of sunset, and you’ll still see it in its “true” color—white, not red. Our eyes are constantly comparing an object against its surroundings. They therefore observe the effect of a shift in the color of illuminating on both, and adjust accordingly.

The eyes can distinguish several million graduations of light and shade of color. Each waking second they flash tens of millions of pieces of information to the brain, which weaves them incessantly into a picture of the world around us.

Yet all this is done at the back of each eye by a fabric of sensors, called the retina, about as wide and as thick as a postage stamp. As the Renaissance inventor and artist Leonardo da Vinci wrote in wonder, “Who would believe that so small a space could contain the images of all the universe?”

1.Visual illusions often take place when the image of reality is ___.

A.matched to six to seven million structures called cones.

B.confused in the body’s sensors of both rods and cones.

C.interpreted in the brain as what must be the case.

D.signaled by about 120 million rods in the eye.

2.The visual sensor that is capable of distinguishing shades of color is called ___.

A.cones

B.color vision

C.rods

D.spectrum

3.The retina send pulses to the brain ___.

A.in short wavelengths

B.as color pictures

C.by a ganglion cell

D.along the optic nerve.

4.Twenty-four still photographs are made into a continuous moving picture just because ___.

A.the image we see usually stays longer than it actually appears.

B.we see an object in comparison with its surroundings.

C.the eyes catch million pieces of information continuously.

D.rods and cones send messages 20 to 25 times a second.

5.The author’s purpose in writing the passage lies in ___.

A.showing that we sometimes are deceived by our own eyes.

B.informing us about the different functions of the eye organs.

C.regretting that we are too slow in the study of eyes.

D.marveling at the great work done by the retina.

答案:CADAB

 



  • 上一个文章:
  • 网站版权与免责声明
    ①由于各方面情况的不断调整与变化,本网所提供的相关信息请以权威部门公布的正式信息为准.
    ②本网转载的文/图等稿件出于非商业性目的,如转载稿涉及版权及个人隐私等问题,请在两周内邮件fjksw@163.com联系.


    | 关于我们 | 联系我们 | 版权申明 | 网站导航 |
    琼ICP备12003406号