When we can see well, we do not think about our eyes very often. It is only when we cannot see perfectly that we come to see how important our eyes are.

    People who are nearsighted can only see things that are very close to their eyes. Many people who do a lot of close work, such as writing, reading and sewing（缝纫）, become nearsighted. Then they have to wear glasses in order to see distant things clearly.

    People who are farsighted（远视的）suffer from 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 remove them.

    When night falls, colors become fainter to the eye and finally disappear. After your eyes have grown used to the dark, you can see better if you use the sides of your eyes rather than the centers. Sometimes, after dark, you see a small thing to one side of you, which seems to disappear if you turn you 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 mistake happens because the center of the eye, which is very sensitive(敏感的) in daylight, is not as sensitive as the sides of the eyes after dark.

    As a Fulbright（富布莱特法案基金）scholar at Yale, I wanted very much to get some individual help from some famous professors, but their office-hours were only once a week and there were always students waiting outside. At first, I was too polite to get their help. Then I realized that Chinese politeness does not work in this society. I needed to be aggressive to get what I wanted. I also noticed that Chinese students or Asian students were very polite in class while American students often interrupted the professor, asking questions and dominating the discussion. The Chinese students were not as aggressive as American students.

    I was impressed by the role of the professor in the class. The professor didn't act as an authority, giving final conclusions, but as a researcher looking for answers to questions together with the students. One linguistic feature of his interacting with his students was that he used many modal verbs-far more than I did in Beiwai. When answering questions, he usually said: “this is my personal opinion and it could be wrong. It would be a good idea if you could read the book I mentioned the other day.” Or,“ You may find the book I recommended helpful.” Or,“You could be right, but you might find this point of view also interesting.” When making comments on students' performances, the professor usually said:” It might have been much clearer if you had taken in some of the ideas we discussed earlier this semester.”

    In China, authorities are always supposed to give wise decisions and correct directions. Therefore students always expect the professor to give an answer to the question. I still remember how annoyed they were when foreign teachers did not provide such an answer. Their expectations from authorities are much higher than those of American students. Once the Chinese students got the answer, they were sure about it. That is why they make far more certain statement than American students. That is why Chinese students find it difficult to use modal verbs because the function of modal verbs is to provide room for negotiation and different ideas.

    From the earliest times, man has been interested in art. People have often worked together to collect and save the world's art treasures.

    Fine art treasures from many countries are kept in an art museum called the Louvre in Paris, France. The works of art have been collected by the people of France over many centuries.

    The Louvre has not always been a museum. The first building was a fort(炮台).In 1190, it was the king's castle with high walls and a round tower. It had a moat to prevent his enemies from walking in.

    Over the years, the number of buildings around the castle grew. By 1350, the castle was no longer needed as a fort. The Louvre became a palace home for French kings and queens.

    During times of peace, new treasures were brought in. During days of war, many treasures were stolen, and the buildings were damaged.

    When Francis I became king of France in 1515, he brought in artists from many countries. One of the artists was Leonardo Da Vinci from Italy. Da Vinci's "Mona Lisa" is the best known painting in the museum today.

    In 1793, the Louvre became a public museum, just as it is now. It is a place where art treasures have been saved for everyone to enjoy.

    A new study warns that about thirty percent of the world's people may not have enough water by the year 2025.

    A private American organization called Population Action International did the new study. It says more than 335 million people lack enough water now. The people live in 28 countries. Most of the countries are in Africa or the Middle East.

    P-A-I researcher Robert Engelman says by the year 2025, about 3,000 million people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet the amount of water on the earth stays the same.

    Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.

    The report says lack of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr Engelman says there are problems all over the world because of diseases, such as cholera, which are carried in water. Lack of water may also result in more international conflict. Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.

    The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture.

    The report also says long-term solutions to the water problem must include controls on population growth. It says countries cannot provide clean water unless they slow population growth by limiting the number of children people have.

    Humans make mistakes. Even surgeons with years of experience are not infallible. But what if these doctors could pool their knowledge and experience together and create a surgical standard of care, to be carried out by machines?

    That's the idea behind surgical robots, which may soon perform most surgeries, from sewing up tiny wounds to performing heart procedures. Many of these operations are, in fact, already completed with the assistance of robots. But a recent test suggests that robots in the operating room may soon go a step further, performing on soft tissue completely on their own, from start to finish.

    The Smart Tissue Autonomous Robot（STAR）, successfully completed surgeries on pigs. "We're the first group to develop autonomous robotic surgery with soft-tissue surgery, and when compared to standard operation, it's better, "says Peter Kim, professor of surgery. "The idea is not to replace surgeons；it will make the surgeons better and make the procedures safer. "

    A recent Mayo Clinic study found that major surgical errors-including operating on the wrong site or side of the body, or even leaving tools or objects inside the patient-occur every one out of 22, 000 procedures. That's rare, but robots like STAR would aim to lower the number even further.

    In the da Vinci surgical system, surgeons place their arms inside instruments and use their hands to control the movement of robotic tools on the operating table from afar. The robot's every major move is controlled by surgeons, and thus its results may vary based on the surgeon's training or experience.

    STAR, on the other hand, is entirely autonomous. It's not only able to work on its own and perform surgeries with a more flexible "hand", but it's able to react to the unexpected incidents. Cutting into hard tissue like bones is one thing, but operating on moving soft tissue is far more complex. STAR reacts to a changing environment, similar to how self-driving cars are programmed to not only drive on the highway, but also react to another driver making a mistake and getting in your way.

    David Cameron is urging today's youngsters to abandon French to concentrate on the tongue of the future—Mandarin(普通话)。

    Cameron said: "I want Britain linked up to the world's fast-growing economies. And that includes our young people learning the languages to seal tomorrow's business deals.”

    "By the time the children born today leave school, China is to be the world's largest economy. So it's time to look beyond the traditional focus on French and German and get many more children learning Mandarin.” To strengthen his message , he quoted Nelson Mandela—the former president of South Africa who said "If you talk to a man in a language he understands that goes to his head; if you talk to him in his own language that goes to his heart.”

    Cameron said that a partnership between the British Council (英国文化协会) and Hanban will double the number of Chinese language assistants in the UK by 2016 and provide increased funding to schools of offering Mandarin as a language choice. In a development of the UK—China School Partnership programme , funding will also be provided for 60 headteachers to make study visits to China in 2014.

    In recent research the British Council found only 1% of the adult population speaks Mandarin to a level that allows them to conduct a basic conversation. Just 3,000 pupils in England, Wales and Northern Ireland entered for Chinese languages GCSEs in 2013, putting it far behind the traditional choices of French with 177,000, Spanish with 91,000 and German with 62,000 entrants(加入者), as well as Urdu, Polish and Arabic.

    Professor Dame Helen Wallace, the British Academy's foreign secretary, said, " a lack of qualified teachers could be a barrier to improve its popularity.”

    Laura Chan, one of the co—founders of a bilingual Mandarin—English primary school, said the prime minister's announcement was good news for the status of Mandarin. She said, "It's a great help. It will increase people's awareness of Mandarin as a language they can learn.”