When we can see well, we do not think about our eyes often. It is only when we cannot see perfectly that we come to know how important our eyes are. People who are nearsighted can see things that are very close to their eves. Many people who do a lot of close work, such as writing and reading, become nearsighted. Then they have to wear glasses in order to see distant things clearly. People who are farsighted face just the opposite problem. They can see things that are far away, but they have difficulty reading a book unless they hold it at arm's length. If they want to do much reading, they must get glasses too.
Other people do 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 of cataracts(白内障). Long ago these people often became blind. Now, however, it is possible to operate on the cataracts and take them away.
When night falls, colours become fainter(黯淡) to the eves and finally disappear. After your eyes have got used to the dark, you can see better if you use the side of your eyes rather than the centres. Sometimes, after dark, you see a small thing to one side of you, which seems to disappear if you turn your head in its direction. This is because when you turn your head, you are looking at the thing too directly. Men on guard duty sometimes think they see something moving to one side of them. When they turn to look straight at it, they cannot see it any more, and they believe they were mistaken. However, this happens because the centre of the eye, which is very sensitive(敏感的) in daylight, is not as sensitive as the sides of the eye after dark.
【小题1】We don't know that our eyes 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 |
【小题2】According to the passage, a ___________ is more likely to be nearsighted.
| A．policeman | B．doctor | C．football player | D．guard |
【小题3】People who are farsighted ___________.
| A．cannot do a lot of close work without glasses |
| B．can only see things that are very close to their eyes |
| C．have difficulty reading a book if they hold it at arm's length |
| D．have the same problem as the nearsighted people |
【小题4】To see a small thing at night, it is better to look ___________.
| A．with wide open eyes | B．with half shut eyes |
| C．straight at it | D．in a little different direction |
【小题5】Which of the following is true according to the passage?
| A．Guards often make mistakes at night. |
| B．People with cataracts should wear glasses too. |
| C．Some people can't see clearly because there is something wrong with their eye shape. |
| D．People who are nearsighted cannot see things far away |
