Seeing in Stereo
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(影像)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 underlined word “perceived” in Paragraph 3 means ．
4．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
Mike Myers is a teacher at Chauncey Rose High School in Terre Haute, Indiana. Last year, he taught his students about the world’s rain forests. They learned that rain forests are important because the plants and animals of the rain forest give us food, wood, and medicine.
Destruction of the world’s rain forests is a serious problem. Unluckily, rain forests are disappearing at a rate of 80 acres per minute! As part of a class project, Myers’ students bought three acres of rain forest in Costa Rica. They paid $25 per acre. The students hope that the land they bought will be protected and not destroyed. The students became so interested in rain forests that they decided to get a closer look at a real rain forest.
So last June, Myers and four of his students took a boat ride down a river. They saw alligators and crocodiles. In the middle of the week, a guide took Myers and his students into the rain forest. “The monkeys were not happy that we were in their forest. They broke small branches off the trees and threw them at us,” one of the students said, “It was a great learning experience for all of us,” said Myers.
Each student chose something specific about Costa Rica to study involving the plants, animals, food, and culture. During the last few days the group had time to do fun activities. They went whitewater rafting and horseback riding, and visited Costa Rica’s active volcano.
Myers hopes to make the trip every year with a different group of kids.
1．How much did Myers’ students pay for the rain forest they bought?
2．What did Myers and his students do at the beginning of the trip?
A．They went into the rain forest
B．They bought acres of rain forest
C．They took a boat ride down a river
D．They visited Costa Rica’s active volcano
3．When the monkeys saw Myers and his students, they______.
C．jumped off the trees
D．left the rain forest
4．The passage mainly shows that Myers and his students______.
A．did something to protect rain forest
B．wanted to buy the rain forest in Costa Rica
C．were interested in the culture of Costa Rica
D．went to the rain forest for various fun activities