When we cansee well, we do not think about our eyes very often. It is only when we cannotsee perfectly that we come to see how important our eyes are. People who arenearsighted can only see things that are very close to their eyes. Many peoplewho do a lot of close work, such as writing, reading and sewing, becomenearsighted. Then they have to wear glasses in order to see distant thingsclearly. People who arefarsighted( 近视的 ) suffer from just theopposite problem. They can see things that are far away, but they havedifficulty reading a book unless they hold it at arm’s length. If they want todo much reading, they must get glasses too. Other peopledo not see clearly because their eyes are not exactly the right shape. This, too,can be corrected by glasses. Some people’s eyes become cloudy because ofcataracts( 白内障 ). Long ago these peopleoften became blind. Now, however, it is possible to operate on the cataractsand remove them. When nightfalls, colours become fainter to the eye and finally disappear. After your eyeshave grown used to the dark, you can see better if you use the sides of youreyes rather than the centers. Sometimes, after dark, you see a small thing toone side of you, which seems to disappear if you turn you head in itsdirection. This is because when you turn your head, you are looking at thething too directly. Men on guard duty sometimes think they see something movingto one side of them. When they turn to look straight at it, they cannot see itanymore, and they believe they were mistaken. However, this mistake happensbecause the center of the eye, which is very sensitive( 敏感的 ) in daylight, is not assensitive as the sides of the eyes after dark. 1. We don’t know that oureyes are of great importance until _____. A. we think about our eyes B. we cannot see clearly C. we wear glasses D. we have to do much reading 2.According to the passage,a _____ is more likely to be nearsighted. A. tailor B.doctor C. guard D. painter 3. Those who suffer fromcataracts _____. A. will become blind B. cannot be cured ( 治愈 ) C. may be cured D. must move to other places 4. People who arefarsighted _____. A. cannot do a lot of closework without glasses B. can only see things thatare very close to their eyes C. have difficulty reading abook if they hold it at arm’s length D. have the same problem asthe nearsighted people 5. to see a small thing atnight, it is better to look ______. A. with wide open eyes B. with half- shut ornarrowed eyes C. straight at it D. in a slightly differentdirection