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.

   Ellen Mac Arthur arrived back in England after sailing around the world. She is now the fastest

person to sail around the world _____. The _____ journey took her 71 days, 14 hours, 18 minutes and 35 seconds, without a single _____ on land at any time. She was just 28 years old. Around 8,000 people were waiting at the harbour to _____ congratulations to her. She left _____ on 28 November,2004,and travelled about 43,000 kilometres to get back home.

Ellen _____ a long time preparing both her body and her mind for the long journey. She only let herself sleep for less than 20 minutes at any one time during her _____. She had no one else to talk to in the 71 days. She had a small stove(炉) to heat the frozen(冰冻的) meals she had taken with her. She had to sail _____ to avoid danger. She often faced dangerous storms, but she never thought of _____.

Ellen is now famous all over the world. Her story ______ us that if you believe in yourself, you can achieve anything.