Reading can be a social activity. Think of the people who belong to book groups. They choose books to read and then meet to discuss them. Now, the website BookCrossing.com turns the page on the traditional idea of a book group.

    Members go on the site and register the books they own and would like to share. BookCrossing provides an identification number to stick inside the book. Then the person leaves it in a public place, hoping that the book will have an adventure, traveling far and wide with each new reader who finds it.

    Bruce Pederson, the managing director of BookCrossing, says, “The two things that change your life are the people you meet and books you read. BookCrossing combines both.”

    Members leave books on park benches and buses, in train stations and coffee shops. Whoever finds their book will go to the site and record where they have found it.

    People who find a book can also leave a journal entry describing what they thought of it. E-mails are then sent to the BookCrossing to keep them updated about where their books have been found. Bruce Peterson says the idea is for people not to be selfish by keeping a book to gather dust on a shelf at home.

    BookCrossing is part of a trend among people who want to get back to the “real” and not the virtual(虚拟). The site now has more than one million members in more than one hundred thirty-five countries.

    If you are taking vitamin supplements to reduce your risk of heart disease or cancer, a group of health experts want you to know that those vitamins may actually increase your risk of cancer.

    The US Preventive Services Task Force came to this conclusion after reviewing dozens of studies.

    Nearly half of adults in the US take at least one vitamin or mineral supplement on a regular basis. These pills are advertised as a way to promote general health. In some cases, manufacturers promote them as cancer fighters and heart protectors.

    Studies in animals and in laboratory dishes suggest that oxidative(氧化性的) stress contributes to diseases like cancer and heart disease. If so, there is a reason to believe that antioxidants—including beta-carotene, vitamins A, C, and E—could be useful as preventive medicines.

    But when the Task Force examined the medical evidence on vitamins, it found “inadequate(不充分的) evidence” to support the claims that vitamin and mineral supplements benefit healthy adults.

    “Cardiovascular(心血管的) disease and cancer have a significant health impact in America, and we all want to find ways to prevent these diseases,” Dr. Virginia Moyer, who heads the Task Force, said in a statement. But so far, she added, the medical evidence does not show that taking vitamins is helpful in this regard.

    However, the Task Force did find “adequate evidence” that people with a raised risk for lung cancer actually increase their risk further by taking beta-carotene, a precursor of vitamin A.

    The Task Force recommendations of taking vitamins regularly apply to healthy adults aged 50 and older who don't have “special nutritional needs”. The advice does not apply to children, women who are pregnant or may become pregnant, people with chronic illnesses, or people who have to take supplements because they can't get all their essential nutrients from their diet.

    In most situations, light helps us see. But when it comes to looking at the night sky, light is actually a kind of pollution. It prevents our view of some of life's most striking sights: stars, planets, and even galaxies (银河系).

    "When I was a little boy, I loved the night sky. I remember looking up and the sky was filled with stars. I became an astronomer because I was amazed by their beauty," says Robert Gent, "Now in most big cities kids can't see the stars like I did."

    Normally, about 2，500 individual (单个的) stars are visible to the human eyes without using any special equipment. But because of light pollution, you actually see just 200 to 300 and fewer than a dozen from some cities. Only one in three Americans can see our own galaxy with the naked eyes. Those people live far away from the lights of big cities, office buildings, and shopping malls.

    Fortunately, there's an inexpensive and useful way. If we shine lights down at the ground instead of up into the sky, and use lower brightness levels, we can save big amounts of energy and keep the beauty of the night skies. Many cities and towns have passed laws limiting lights at night, making sure enough shine for safety without creating much light pollution.

    Light pollution affects more than our view of the heavens and can harm wildlife. Migrating birds (候鸟) sometimes fly over cities and become confused by the brightness, flying in circles until they drop from exhaustion. Sea turtles need dark beaches for nesting and won't approach bright lights. Too much light at night may even affect human health. For all these reasons, researchers are working on ways to use lights only when and where they are truly needed. Everyone deserves to look up at the sky.

    The pupils of Grangetown High have been busy getting to know their newest and tallest classmate — a 7-meter-tall giraffe outside their school.

    The giraffe is a huge sculpture (雕像). The school's headmaster noticed it in an artist's garden as he drove past one day, and thought it would be perfect for his school. “I knew everyone would love it," he said, "because our basketball team is known as the Grangetown Giraffes, and they wear giraffes on their shirts. So I asked them to write to the artist, asking how much it would cost to buy the giraffe. He was very kind and got it ready to deliver (递送) in six weeks — all for nothing! It was expected to arrive one Sunday morning, so that the pupils would see it when they got to school on Monday — at that time they had no idea that we were getting it."

    The artist, Tom Bennett was a university professor of chemistry before he retired in 2012 and only took up metalwork a couple of years ago. "I've always drawn pictures," he said. I can even remember doing it on my first day at school — I drew a horse. I wanted it to be the best horse picture ever, but I don't think I succeeded."Tom's first metalwork was a bicycle on which he and his wife could go cycling together, “It was the most uncomfortable bike ever created," he said, "so I gave up making bicycles and went into sculpture instead."

    Meanwhile the pupils at Grangetown High are very happy with their new classmate. "We're going to hold a competition to give it a proper name," said one girl. "Everyone likes the expression on its face, so perhaps that will give us some ideas."

    Sometimes people add to what they say even when they don't talk. Gestures are the "silent language" of every culture. We point a finger or move another part of the body to show what we want to say. It is important to know the body language of every country or we may be misunderstood.

    In the USA, people greet each other with a handshake in a formal introduction. The handshake must be firm. If the handshake is weak, it is a sign of weakness or unfriendliness. Friends may place a hand on the other's arm or shoulder. Some people, usually women, greet a friend with a hug.

    Space is important to Americans. When two people talk to each other, they usually stand about two and a half feet away and at an angle (角度), so they are not facing each other directly. Americans get uncomfortable when a person stands too close. They will move back to have their space. If Americans touch another person by accident, they say, "Pardon me" or "Excuse me". Americans like to look at the other person in the eyes when they are talking. If you don't do so, it means you are bored, hiding something, or are not interested. But when you stare at someone, it is not polite.

    For Americans, thumbs-up means yes, very good, or well done. Thumbs-down means the opposite. To call a waiter, raise one hand to head level or above. To show you want the check, make a movement with your hands as if you are signing a piece of paper. It is all right to point at things but not at people with the hand and index finger (食指). Americans shake their index finger at children when they scold them and pat them on the head when they admire them.

    Learning a culture's body language is sometimes confusing. If you don't know what to do, the safest thing to do is to smile.

    To have a successful job interview, you need to make good preparations beforehand. Here are some suggestions on what you should do before the interview.

    ⑴Find out as much as you can about the company. What goods or services do they provide? How long has it been founded? Read articles about it. Talk with people who work there. Perhaps you can look at the company website, or find some information on the Internet.

    ⑵Be sure of the time of the interview, the place and the person you'll see.

    ⑶Think about the kind of questions that the employer might ask. Write out questions and possible answers.

    ⑷Rehearse the interview with family members or friends. They can ask you questions from the list you've prepared and you can try to answer.

    ⑸Dress properly. Don't be too formal or too informal. Choose your clothes, shoes.

    ⑹Wash. Make sure that you are clean, and that your teeth have been freshly brushed.