Part of the fun of watching sports events is following an exciting rivalry (竞争关系).

    But where do all these rivalries come from?

    Some rivalries start because athletes spend a lot of time close to opponents (对手).

    Other rivalries get personal. Things that one rival says that are thought to be not respectful to the other can cause a rivalry, even if the words are misunderstood. And sometimes, rivalries grow just because the athletes don't like each other's personalities.

    Some sports may also be more likely than others to cause rivalries. “Some sports only meet a few times, so there is less chance for rivalries to build,” For example, in sports where athletes perform on their own, such as diving, rivalries might also take longer to appear than in sports in which athletes compete at the same time. But in tennis, players often face each other, and rivalries are more likely to happen.

    So do the rivalries do good or harm to the athletes?

    Some believe that rivalries can be a good thing because they encourage athletes to try harder to win. But rivalries can also become too personal, taking athletes' attention away from their sports.

    Keegan agreed that rivalries often do athletes more harm than good. “They can be a huge distraction (分散注意力的事) and lead to focusing on the opponent more than the game,” he said.

    “Top athletes often have physical and mental training that they follow in order to worry less and prepare to compete”, Gould further explained. An important part of that preparation is preventing from distractions, including rivalries.

    “The better athletes don't care too much about a rivalry – they try to treat every competition the same,” Gould told LiveScience.

    Taylor Swift was born on December 13, 1989, in Wyomissing, Pennsylvania. Swift's family ran a farm. “I had her sitting on a small horse when she was nine months old,” said Swift's mother. “If my dream had gone well, she'd be in a horse show right now.” The only obvious forerunner (先驱) of Swift's musical talent was her grandmother, an opera singer.

    That talent showed itself early: when the family went to see a Disney musical film, Swift would come out of the theater singing all the songs correctly. At the age of 11, she sang “The Star-Spangled Banner” at a Philadelphia 76ers game. The experiences during her pre-teen years encouraged the creativity to go with Swift's talent. As a child, she attended the academically competitive Wyndcroft School in Pottstown, but then switched to public schools in Wyomissing. Although it was her hometown, she didn't know any of her classmates, and she was terrified. Swift began to understand the storytelling feature of country songs, and put her feelings into songs of her own.

    One of her future hits, “The Outside”, was written when she was only 12. “I wrote that about the scariest feeling I've ever felt: going to school, looking at those faces, and not knowing who you're gonna talk to that day,” she said. “In the music, I could never feel the kind of rejection (拒绝) that I felt in middle school.” Swift's parents quickly realized that they had someone special on their hands. They sold their farm when she was 13 and moved the family to Hendersonville, Tennessee.

    Swift had the ability, above all, to put feelings into words with accuracy (准确) far beyond her years. In “Our Song” she wrote, “Our song is the slamming screen door, going out late, tapping on your window.” In the summer of 2006, “Tim McGraw” came out, and almost from the beginning the 16-year-old Taylor Swift was a star.

    Stuck in Neutral by Terry Trueman

    This novel tells the story of Shawn McDaniel,a 14-year-old boy with brain disease.He is highly intelligent,yet unable to move his muscles anti communicate.Through his first-person description,he remains positive about his life, even when people treat him like his brain is damaged.This short novel forces young readers to think about the assumptions they make about people with disabilities,and also addresses euthanasia（安乐死）and quality of life as relevant social problems.

     Angela's Ashes by Frank McCourt

     Frank McCourt's New York Times bestselling memoir（回忆录）tells the story of his life growing up as an extremely poor child in Ireland and how he overcame those circumstances.He wrote the story to inspire young readers to make the most of what they have,and call on them to continue trying and overcome any difficulties they may face.

    The Last Lecture by Randy Pausch & Jeffrey Zazlow

    In 2006,when he was only 45 years old,Randy Pausch suffered from cancer and learned he had only three to six months to live.Inspired by a professor's inspirational lecture,Pausch co-authored a book named The Last Lecture with Jeffrey Zazlow within a few short months.In spite of his disease,the book,is surprisingly encouraging.It encourages young readers to focus on what's truly important in life.

    The Perks of Being a Wallflower by Stephen Chbosky

    This story has become a classic clue to its honest look at the everyday lives of teenagers.Through the eyes of the 15-year-old writer,Charlie,the novel details the daily trails that many teenagers face,but it also deals with social problems like drug abuse.It also focuses on the roles that friendship,family and love play in helping us get through difficult times.

    As an expert on the science of sleep and sleep disorders, Michael Twery believes “People have good understanding about the necessity of sleeping 7-8 hours in bed. But they undervalue the function of napping in day.”

    For example, many Americans do nap. But one-third of adults in the US are also frequently tired. Someone who naps as a way of paying off a sleep debt may not experience the same improvements from napping as a healthy, well-rested person would.

    Also, many people may not want to admit that they take a nap. That only children, the very old, sick or lazy people nap is a common opinion. In fact, Americans sometimes do very strange things. For those who claim they only sleep five hours a night, they may think they are somehow stronger than the average human—superhuman, if you will.

    Luckily, many offices now offer napping rooms in many U. S. cities. While resting in the middle of the work day may seem like a luxury to Americans, napping is very much part of a normal, everyday life in other parts of the world.

China, generally speaking, is a land of nappers. Researchers recently looked at information provided by nearly 3, 000 Chinese adults, aged 65 years or older. Based on their answers, researchers put them into four groups: non-nappers (0 minutes), short nappers (less than 30 minutes), moderate nappers (30-90minutes), and extended nappers (more than 90 minutes).

    The study found that the hour-long nappers did better on the tests than those who napped for shorter and longer periods. Keep in mind, however, that these are the findings for those over the age of 65.

    Michael Twery notes that an hour long nap may be too long for young, healthy adults. “Currently, 30 minutes is enough to remove the pressure to sleep and will help us feel more awake. If we nap longer, we will get trapped into sleep inertia—a very deep sleep period.”

    The huge T­rex (霸王龙) bends over a large triceratops (三角龙) lying on his side below. With its mouth open wide, the T­rex looks ready to kill the triceratops with a final bite to the triceratops's neck. The display will be found at the National Museum of Natural History.

    The museum has sought a huge T­rex skeleton (骨架) for many years. Before, it used a model of one. But museum director Kirk Johnson says that was never good enough. "It's been kind of deeply embarrassing to be the national museum and NOT have a T­rex," he said. The T­rex display is now the centerpiece of the museum's newest show, which will be available to the public on July 15.

    That T­rex, named Sue, was found in South Dakota. Officials at the museum built a special area for the skeleton. It includes a gift store of all things related to Sue. Sue even has her own Twitter account and a media presentation of her life story.

    In modern times, movies like "Jurassic Park (侏罗纪公园)" have helped grow dinosaur interest for a new generation of young fans. But such movies describe the T­rexes as mostly huge, stupid and dangerous animals, which are true threat in the fighting: quick, intelligent and aggressive hunters in groups.