Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.

    The gene comes in two versions, one of which is found in 99 percent of Europeans. The other is found in 93 to 100 percent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

    Scientists have changed the color of a dark-striped zebra-fish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra-fish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.

    It appears that, like the golden zebra-fish, light-skinned Europeans also have a mutation (变异) in the gene for melanin production. This results in less pigmented skin.

    However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra-fish genes.

    Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), which can cause skin cancer.

    But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

    Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

    The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

    A busy public square in the Chinese city of Nanjing is home to an unusual experiment.

    For almost two months, the country's first “honesty bookshop” has occupied（占据） a sidewalk on HanZhong Road in the city's Gulou District.

    With no cashier or other staff, the store relies on trust for payment.

    Making money isn't the company's main goal and they don't punish those who take books without paying.

    “If they can really finish the books, it doesn't matter if they took the books for free,” Zhu Yu, the marketing director of the company says.

    “In fact, we are really happy to witness so many people taking books from the honesty bookshop.” After browsing the four wooden bookshelves, customers must drop their money in a locked box.

    Prices are set at 30% of the usual cover price. Zhu hopes that his sidewalk store, which sells, on average, 60 books a day, will make more people interested in reading. Like elsewhere, e-books are affecting sales of traditional books, and traditional books and many independent booksellers are struggling.

    Zhu got permission from the city government to use the sidewalk and says he's determined to make it a long-term project.

    He says the store is open every day, except when it rains, and it's locked up each night.

    In September last year, the company laid out 1,000 books and reading lamps on the ground and encouraged people “to go on a date” with a book.

    “Independent bookshops represent the well-being of the city.” Zhu told CNN in 2013, “when a city is losing its bookshops, it's actually losing something in its soul.”

If the success of the Honesty Bookstore is any guide, Nanjing's soul is in pretty good shape.

    You are a new manager at the American branch of your German firm in Chicago. With a few minutes to spare between meetings, you go to get a quick cup of coffee.

    “Hey, David, how are you?” one of the senior partners at the firm asks you.

    “Good, thank you, Dr. Greer,” you reply. You've really been wanting to make a connection with the senior leadership at the firm, and this seems like a great opportunity. But as you start to think of something to say, your American colleague breaks in to steal your spotlight.

    “So Arnold”, your colleague says to your boss, in such a casual manner that it makes your German soul cringe(畏缩), “So what's your Super bowl prediction? I mean, you're a Niners fan, right?”

    The conversation moves on, and you walk silently back to your desk with your coffee. You know how important small talk is in the U.S., and you feel jealous of people who can do it well.

    There's nothing small about the role that small talk plays in American professional culture. People from other countries are often surprised at how important small talk is in the U.S. and how naturally and comfortably people seem to do it — with peers, men, women, and even with superiors. You can be the most technically skilled worker in the world, but your ability to progress in your job in the United States is highly dependent on your ability to build and maintain positive relationships with people at work. And guess what skill is critical for building and maintaining these relationships? Small talk.

    What can you do if you are from another culture and want to learn to use small talk in the U.S. to build relationships and establish trust? Work hard to hone(磨练) your own version of American-style small talk. Watch how others do it. You don't have to mimic what they do; in fact, that would likely backfire because people would see you as inauthentic. But if you can develop your own personal version, that can go a long way toward making you feel comfortable and competence．

    Walt Disney is credited for creating such wonderful things as Donald Duck and Mickey Mouse. However, he cannot take the credit for creating other well-loved characters, such as Cinderella and Snow White. They are almost automatically associated with Disney because Disney turned old fables(寓言) into cartoon movies.

    The original Cinderella varies very much from the Disney version we know today. It started off with the girl mourning her mother's death and going to her tomb three times a day. In addition, there were only birds that helped Cinderella; there was no such thing as a fairy godmother or helpful mice, nor was there mention of a horse and carriage.

    The stepsisters were cruel: they always threw Cinderella's food into the ashes of the fire and made her sleep on the ashes on the floor, hence（因此）her name.

    In the original story, the king's ball actually lasted for three days. With the help of the birds, the girl, beautifully dressed, danced with the prince on all three nights and the prince fell in love with her. However, she broke away from him to rush back home each night. On the last night, the prince placed soothing sticky on the stairs; as Cinderella made her escape, a shoe got stuck on it.

    Here now is where the story becomes unpleasant: when the prince went to the house looking for the girl whose foot fit the shoe, the wicked(邪恶的) stepmother told one of her two daughters to cut off her big toe to fit into the shoe. The daughter did as told. So the prince took her away to be his bride. But when they passed the tomb of Cinderella's mother, the birds called out to the prince,

    “Turn and peep, there's blood in the shoe;the shoe is too small, the true bride waits for you.”

    Realizing he had been tricked, the prince returned the daughter to her mother. The other then had to cut off part of her heel in order to fit into the shoe, with the same result. Only Cinderella's foot fit perfectly and so the prince chose to marry her. The story ends with the wedding day: as Cinderella's two stepsisters followed her, pretending to be devoted to her so that they could enjoy the king's riches, two birds flew by and plucked(啄) out their eyes. Because of their wickedness and falsehood, they had to spend the rest of their days blind.

    The original Cinderella is so different from the Disney version. Thank goodness Disney made such changes; it indeed was a wise move.

    Who could have imagined that a treadmill(跑步机)on wheels would one day become a thing? Lopifit is an unusual means of transportation that allows you to power an electric bicycle by walking on a treadmill.

    Lopifit founder Bruin Bergmeester says it all started when he asked himself the question. "How can I use a treadmill outdoors?" He eventually came up with a design, to which he added an electric engine, and Lopifit was born. The treadmill bicycle is similar to a typical electric bicycle in that the motor only works when the rider puts power in as well. The Lopifit senses it when you walk on the treadmill and uses the motor to turn a drive chain at the back part of the treadmill, helping you reach a top speed of 17 miles per hour.

    To use the Lopifit, simply turn on the battery and use your feet to slide the treadmill backwards and activate (激活) the motor. Then get on and enjoy the ride! If you need speed, just walk on the treadmill, and if you want to coast, all you have to do is stay still and admire the view. To stop, you have two hand brakes available.

    The Lopifit first hit the streets in 2014 and, unsurprisingly, became an instant hit. That was actually quite challenging for the company, because it started get inquiries and calls for orders, but it was nowhere near ready for mass production. The unique treadmill bicycle became available this year, and Lopifit is struggling to keep up with demand, despite the high price tag of $ 2,115.

    But despite having a very loyal fan-base of so-called Lopifitters, the creative means of transportation also has naysayers who simply consider the invention stupid and unnecessary. They basically believe that if you're going to walk, you might as well do it the old-fashioned way. But the Lopifit does have the unique advantage of helping you walk really fast without breaking a sweat, or walking at cycling speed, if you will.

    Some students bring good luck charms（幸运符）to school on test days. They might keep a four-leaf clover in their pocket or wear a pair of lucky underwear. {#blank#}1{#/blank#}  there are better ways of doing well on a test.

    When you get the test, don't forget to put your name on it. Then, take a quick look at each page. A long test may have different sections. Notice how many marks each section is worth. Like a runner, you will want to be careful about your pace. {#blank#}2{#/blank#} you will want to leave yourself enough time for the sections that are worth the most marks.

    {#blank#}3{#/blank#} Read the instructions and questions very carefully. Make sure you understand what you are being asked to do. If you do not understand a question, ask your instructor. If you feel nervous, you may want to build your confidence by starting with the questions that arc easiest for you.

    During a reading test, it can help to do a quick pre-reading exercise you have been taught, even if it is not part of the instructions. For example, try scanning the text to figure out the topic before you rend the whole thing more carefully. Then think about what you already know about the topic. Predict the details that might be in the reading. For a writing test, pre-writing is a very important first step, Brainstorm your ideas and organize them before you start writing. {#blank#}4{#/blank#}

     Before you hand in your test, review your answers. Check your grammar and spelling. Make sure your instructor will be able to read your handwriting. {#blank#}5{#/blank#}

    Follow these tips and, if your lucky underwear doesn't work, you will have a solid back-up plan in place.

A. While these things can't hurt,

B. Whenever you finish your test,

C. Be sure that you answered every question.

D. You can answer your questions one by one.

E. Now you are ready to begin answering the questions.

F. If you have a limited amount of time to complete the test,

G. These activities warm up your brain so that it will work more efficiently.