Question

【題目】 Have you wondered why you have two eyes and why they are set close together on the front of your face? The reasons are simple and important to the way you see the rest of your world．

Your eyes are like two small cameras. A camera catches an image of an object and records it on film．Similarly，when you look at something，each eye takes in what it sees and sends this image to the back of the eyeball．Because your eyes are set close together，they view the world from about the same height but from slightly different angles. Working as a team, the eyes send the images to your brain, which puts them together into a single, centered image.

Seeing in stereo means seeing with two eyes working together，which is called stereoscopic sight．This allows you to view the world in three dimensions，or 3-D．Seeing depth helps you to judge the distance between you and the objects you see and to adjust to the changing angle at which you see something as you move closer to or farther away from it．If images are coming from only one eye, however，only two of these dimensions-height and width-can be perceived．A world seen with one eye is thus two-dimensional，as in a photograph．

Now consider why your two eyes are on the front of your face．Think of other animals with this same arrangement．They are all animals that hunt，like lions and wolves．Their eyes face directly in front of them．This provides a field of sight about 180 degrees wide，which is called binocular sight．On the other hand，animals that are hunted have eyes on the sides of the head，which provides nearly 360-degree field of sight．In order to stay alive，they need to see things coming from the sides and from behind．However，without stereoscopic sight，they have difficulty determining how far a danger is．

With sight both stereoscopic and binocular，humans share with animal hunters the ability to see from side to side and to accurately determine the distance．If you think it would be great to have another type of sight，perhaps with hundreds of tiny eyes like many insects do，think again! Each tiny insect eye sees only a tiny part．Besides，what if you needed glasses? Be glad for the eyesight that you have．

【1】According to the passage，an eye is like a camera because both

A. can record images

B. can imagine objects

C. provide centered images

D. work at the same height

【2】Stereoscopic sight is a result of having

A. a three-hundred-sixty-degree field of sight

B. hundreds of eyes，all seeing parts of an image

C. two eyes close to one another that work together

D. one eye on either side of the head，each seeing a different image

【3】The author implies that “seeing in stereo”

A．is similar to the way cameras work

B．is an ability humans are fortunate to have

C．would be better for a wider field of sight

D．helps people to have better sight than animals

Answer 1

【答案】

【1】A

【2】C

【3】B

【解析】

試題分析：本文講述了什么是立體視覺，介紹了人眼是如何工作的，以及人眼所處位置對定位的影響等信息。人類應該為有這樣的眼睛而感到感激，因為眼睛對生存非常重要，無論是動物還是人類。

【1】細節(jié)分析題。第二段“A camera catches an image of an object and records it on film．”，攝像頭可以捕捉物體的影像。故選A.

【2】細節(jié)分析題。第二段“Because your eyes are set close together，they view the world from about the same height but from slightly different angles. ”，可知兩只眼睛距離很近是為了在同一高度，以及減少角度誤差；第三段第一句表示，立體視覺就是兩只眼睛一起工作，可以使我們看到是一個立體的世界。故選C.

【3】推理判斷題。最后一段“Be glad for the eyesight that you have．”可知我們對擁有這樣一雙眼睛要心存感激，這是我們與生俱來的財富。故選B.