When the sun sets in Hong Kong, the city skyline comes alive. Billboard（广告牌）lights flash, and light up the crowded streets. The colorful lights from the tall buildings are one of the city's main attractions.

    “Oh, my god. The lights are so amazing. We love it. It's so nice.” said one visitor.

    But this appreciation is not shared by everyone in Hong Kong. Lat year then government reported a record number of complaints. The curtains may be drawn. But residents argue the bright light outside is hard to escape. “We receive some complaints about the light pollution. They find it very hard to sleep or they have disturbance from the light outside.”

    Scientists at the University of Hong Kong spent 18 months studying levels of light pollution and collecting more than 5 million measurements. They found Hong Kong one of the world's worst “victims”. The lights pollution condition in Hong Kong was extremely severe. Particular in cities, the night sky brightness, as well as the lights, is a few hundred times over the level of that of a night sky without light pollution. In cities such as Seoul, London, Shanghai and Paris, billboard lighting is under control. And there are punishments for people who go against the law.

    But in Hong Kong, there are no laws. A volunteer regulation called Charter of External Light（户外灯光约章）encourages visitors to switch off between 11 p.m. and 7 p.m. The critics say it's not enough to make a difference. The government says 4800 businessmen have signed up to the Charter so far. And it's satisfied that it's working.

    But not everyone is convinced and some residents are taking upon themselves to act. Zoe Chow led a campaign to have a commercial building switch off their midnight. She won but she believes the lights will eventually turn back on. “I know that the building has signed the Charter of External Light. But it is voluntary, not mandatory（强制的）.

    Cooperation at work is generally seen as a good thing. The latest survey by the Financial Times of what employers want from MBA graduates found that the ability to work with a wide variety of people was what managers wanted most. But managers always have to balance the benefits of teamwork, which help ensure that everyone is working towards the same goal, with the dangers of “groupthink” when critics are reluctant to point out a plan's drawbacks for fear of being kept out of the group. The disastrous Bay of Pigs invasion of Cuba in 1961 was a classic case of groupthink. Skeptics were reluctant to challenge John F. Kennedy, the newly elected American president.

    Modern communication methods mean that cooperation is more frequent. Workers are constantly in touch with each other via e-mail messaging groups or mobile calls. But does that improve, or lower performance? A new study by three American academics, tried to answer this question. They set a logical problem (designing the shortest route for a travelling salesman visiting various cities). Three groups were involved: one where subjects acted independently; another where they saw the solutions posted by team members at every stage; and a third where they were kept informed of each other's views only intermittently.

    The survey found that members of the individualist group reached the premier solution more often than the constant cooperators but had a poorer average result. The intermittent cooperators found the right result as often as the individualists, and got a better average solution. When it comes to ideal generation, giving people a bit of space to a solution seems to be a good idea. Occasional cooperation can be a big help: most people have benefited from a colleague's brainwave or (just as often) wise advice to avoid a particular course of action.

    Further clues come from a book, Superminds, by Thomas Malone of the Massachusetts Institute of Technology. He says that three factors determine the collective intelligence of cooperating groups: social intelligence (how good people were at rating the emotional states of others); the extent to which members took part equally in conversation (the more equal, the better); and the cooperation of women in the group (the higher, the better). Groups ranked highly in these areas cooperated far better than others.

    In short, cooperation may be a useful tool but it doesn't work in every situation.

    In this Pennsylvania city, Pittsburgh is shrinking but getting wealthier. Since 2000, its population has declined by 95,000 while its income per capita (人均) has shot up 24 percent. The trend is taking hold in many other cities, like Buffalo in New York, Providence in Rhode Island and New Orleans.

    Some of these areas have created more high-paying jobs in energy, health care or education. Others have managed to reshape their manufacturing (制造业) for a new economy. Higher-paying jobs have a greater effect because they create demand for additional services. “The story in Pittsburgh is very positive, and other areas are looking at it as an example of the transformation that might be possible,” said Guhan Venkatu, who wrote an economic history of the area called “Rust and Renewal” for the Federal Reserve Bank of Cleveland.

    Carnegie Mellon University and the University of Pittsburgh have helped bring tech jobs and innovation (革新) to the area by sponsoring tech centers that help graduates start companies without moving to Silicon Valley or San Francisco. This has helped keep Pittsburgh's educated young population growing even as the entire population in the city has dropped.

    Pittsburgh has more STEM (science, technology, engineering and math) jobs than other shrinking cities, about 80,000 or 7% of all jobs. STEM jobs add productivity and income growth to the area. Manufacturers of high-tech medical equipment in the Pittsburgh area also have doubled employment in the last 10 years.

    However, some experts question whether growing income per capita can really make up for a declining population. According to Patrick Adler, a researcher at the University of Toronto, population loss does matter if it means lower-skilled workers have fled because of a lack of opportunity. What's more, high-paying jobs in education and health care can disappear if the population declines too greatly. So it'd be wise to find ways to increase the population.

    Tokyo is one of those places that you can love and hate at the same time.

    In Tokyo there are always too many people in the places where I want to be. Of course there are too many cars. The Japanese drive very fast, but in Tokyo they often spend a long time in traffic jams. Tokyo is not different from London, Paris and New York in that. It is different when one wants to walk.

    At certain times of the day there are a lot of people on foot in London's Oxford Street. But the streets near the Ginze in Tokyo always have a lot of people on foot， and sometimes it is really difficult to walk. People are very polite; there are just too many of them.

    The worst time to be in the street is at 11:30 at night. That is when the nightclubs are closing and everybody wants to go home. There are 35,000 nightclubs in Tokyo, and you do not often see one that is empty.

    During the day，most people travel to and from work by train. Tokyo people buy six million train tickets every day. At most stations, trains arrive every two or three minutes, but at certain hours there do not seem to be enough trains. Although they are usually crowded, Japanese trains are very good. They always leave and arrive on time. On a London train you would see everybody reading a newspaper. In Tokyo trains everybody in a seat seems to be asleep, whether his journey is long or short.

    In Tokyo, I stood outside the station for five minutes. Three fire-engines raced past on the way to one of the many fires that Tokyo has every day. Tokyo has so many surprises that none of them can really surprise me now.

Swimming and English Learning

    Can you swim? Do you like swimming? Yes? Well, how can you learn to swim? I think the best way is to go into the water and learn. I'm afraid you'll never learn to swim just by reading books about swimming or looking at others swimming. It's the same with the English study. We must practice, practice and practice.

    Listening and speaking are very important for beginners. The children in English-speaking countries first listen to others. Then they try to imitate and speak. We can listen to English programs on radio. You may just understand a few words. It doesn't matter. Just be relaxed, try to catch every word.

    Somebody may be a good listener. But he dare not speak. He's afraid of making mistakes. You know we sometimes make mistakes when we speak Chinese. Don't be afraid. We must be brave. If you really want to learn English well, you must try to speak with everyone so long as he knows English. Whether you know him or not is not important when there's nobody to talk with, you can talk to yourself in English. It's interesting and also a good way to practice your spoken English. Remember, the more you speak, the fewer mistakes you'll make.

    Reading and writing are more important for senior school students. First we must choose the books we're interested in. A lot of reading will improve your language sense. This is the most important.

    Keep writing English diaries. We can also write English articles. You may even post them to English magazines. Don't be afraid of failure. Failure is the mother of success.

    Easier said than done. Well, let's do more practice from now on. I'm sure you'll learn English well in this way.

    The earliest known copy of Leonardo da Vinci's Mona Lisa—thought to have been painted at the same time as the original masterpiece—has been discovered at the Prado Museum in Madrid, Spain. The work offers art-lovers an attractive clue to what the model for the world's most famous painting really looked like. Controllers of the museum found the picture hidden beneath layers of paints during restoration work on a picture initially thought to have been a later replica(exact copy) of the Mona Lisa.

    The restored version shows the same woman that Leonardo depicted (描画), against a landscape similar to that shown in the background of the original, which now hangs in the Louvre in Paris. And while the features of Leonardo's Mona Lisa have been dulled by centuries of dirt and layers of cracked paints—which are unlikely ever to be removed—in the recently-rediscovered copy, she appears fresher-faced and younger than her better-known "twin".

    News of the find was revealed at a meeting at London's National Gallery, linked to its "Leonardo da Vinci: Painter at the Court of Milan" exhibition. "This sensational (轰动的) find will transform our understanding of the world's most famous picture," the Art Newspaper reported, adding that the clues found on the Madrid version suggest that the original and the copy were begun at the same time and painted next to each other, as the work went on.

    Miguel Falomir, manager of Italian painting at the Prado, told reporters that expert analysis suggested a strong link between Leonardo and the artist who painted the copy. "The painting was done in the painter's own workshop," he said. "It is absolutely consistent with Leonardo's work, but Leonardo didn't actually do any work on it himself."