In American schools there is something called Homecoming Day. Many high schools and colleges with a football team have a homecoming game. This can be the most important event of the year except graduation or commencement day(毕业典礼)．Students plan Homecoming Day for many weeks in advance.

    Several days before Homecoming，students start to decorate the school. There are signs to wish luck to the team，and many other signs to welcome all the graduates. Many people still come to Homecoming twenty or thirty years after their graduation.

    The members of school clubs build booths(摊位) and sell lemonade(柠檬)，apples and sandwiches. Some clubs help to welcome visitors.

    During the day people like to look for teachers that they remember from long ago. Often they see old friends and they talk together about those happy years in school.

    Everyone soon comes to watch the football game. When the game is half over，the band comes onto the field and plays school songs. Another important moment is when the Homecoming Queen or King appears. All the students vote a most popular student. It is a great honor to be chosen.

    Homecoming is a happy day，but it is not perfect unless the football team wins the game. Even if the team loses，the students still enjoy Homecoming. Some stay at the school to dance，and others go to a party. For everyone it is a day worth remembering.

    When we say older people shrink,we don't mean they become tiny enough to fit in your pocket!We just mean that it's common for older people to become a little shorter over time.This kind of shrinking can't be stopped, although people can slow this process.But why does shrinking happen at all?

    Because of gravity,cushions between the bones in the spine（脊骨）get compressed（压缩）,which makes a person lose a little height and become shorter.

    Another reason why some older people shrink is because of osteoporosis（骨质疏松）.Osteoporosis occurs when bone is broken down and not enough new bone material is made.Over time,bone is said to be lost.Bones become smaller and weaker and can easily break if someone with osteoporosis is injured.

    Older people—especially women,who generally have smaller and lighter bones to begin with—are more likely to develop osteoporosis.As years go by,a person with osteoporosis can get small breaks in bones that are called compression fractures.These breaks cause collapse of the spine and over time the person with osteoporosis can become hunched over（驼背）.

    Did you know that every day you shrink a little,too?You aren't as tall at the end of the day as you are at the beginning.That's because as the day goes on,water in the disks of the spine gets compressed due to gravity,making you just a tiny bit shorter.Don't worry,though.Once you get a good night's rest,your body recovers,and the next morning,you're standing tall again!

    Smoking and drinking alcohol can make this problem worse.Want to do something right now to build strong bones?I believe what I say will help you.

Do you believe that things are connected for no scientific reason at all? For example, do you avoid saying the word "four" to avoid bad luck? If so, you have a superstition (迷信). And you're not alone — all kinds of people have them.

For example, Portugal's soccer superstar Cristiano Ronaldo always steps onto the pitch (球场) with his right foot first, according to The Telegraph. And sports players are not alone in having superstitions. A visitor once asked the Nobel Prize winning scientist Niels Bohr whether he really believed that the horseshoe he'd hung at his country home was lucky. "Of course not," the Danish physicist said. "But I understand it's lucky whether you believe in it or not."

One recent study found that even scientists at MIT and other top US schools tended to look for a meaning in natural events, similar to the connection between stepping on the pitch and playing soccer well, according to The Atlantic. When the researchers gave the scientists little time to answer questions, they were twice as likely to agree with statements such as "Trees produce oxygen so that animals can breathe" as they were when they had more time to think about their reply.

It seems that fear can make people think differently in this way, too. In a British study, students imagined meeting a "witch" who said she would cast (施魔法) an evil spell(符咒) on them. About half said a scientist should not be worried about the spell. Yet each of them said that, personally, they wouldn't let the witch do it to them.

So why are so many of us superstitious? Well, it seems to be our way of dealing with the unknown. "Many people quite simply just want to believe," Brian Cronk, a professor of psychology at Missouri Western State University, said in a 2008 interview. "The human brain is always trying to work out why things happen, and when the reason is not clear, we tend to make up some pretty bizarre (古怪的) explanations."

    And these explanations aren't completely unhelpful. In fact, superstitions can sometimes work and bring real luck, according to psychologists at the University of Cologne in Germany in the May 2010 issue of the journal Psychological Science. They found that believing in something can improve performance on a task like an exam.

    So, what about you? What superstitions do you follow to keep you safe and successful?

    Eleven leatherback turtles (棱皮龟) are swimming across the Pacific Ocean to the Galapagos Islands in a "race". It will be reported online to attract people's attention to the situation of the endangered (濒危的) animals.

    People have put small tracking devices (跟踪装备) on the turtles so that they can monitor their journeys as they head south from their birthplace to their feeding grounds near the Galapagos, about 1,500 km away.

    People can choose a turtle online and track it at http://www.greatturtlerace.com. The turtle that travels furthest in two weeks' swimming will be the winner.

    There is no prize for the winner of the "race". Rather, they just want to help people take notice of the dangers facing the animal that has lived in the oceans for 100 million years.

    Scientists say 95 percent of the turtles in the Pacific Ocean have disappeared in the last 20 years, because of human activities like fishing, stealing their eggs and building near their homes.

    Thousands of leatherback turtles lived at Playa Grande 10 years ago, but the number has dropped below 100 in the last 5 years.

    The leatherback turtle "race" will not be broadcast on TV at the same time because the turtles leave Costa Rica at different times. Instead, a group will provide a day-to-day showing of the first 14 days of their journeys at the same time as if they were racing.

    The activity will collect money to protect Playa Grande.

Emilia Dobek traces her interest in space and the universe back to third grade when she and her father watched a blood moon—a total lunar eclipse (月蚀)—on the roof of their house.

    Now a seventh-grader at East Prairie Elementary School, Dobek recently won the national Discovery Education Lockheed-Martin Beyond Challenge by designing a space station for travelling to Mars.

    She says that night watching the lunar eclipse started a strong desire in her that has yet to run out of fuel. So when her teacher Andrea Smeeton received information about the national challenge, Smeeton said she immediately had one student in mind.

    "I knew she would love the challenge and that she would go way beyond in her search," Smeeton said. "She immediately started researching bone density (密度) of astronauts and how to have food on Mars."

    "My design will ensure the safety of the astronauts but also make sure their comfort is out of this world," Dobek says.

    Dobek's design calls for building the MSS or Mars Storage Station to put the supplies in. It also includes the SGF or Self-Crowing Farm, and she details how it would work with the elements on Mars.

    Then there is physical and leisure activity for the astronauts under Dobek's design. A simulation (模拟装置) allows astronauts to choose their exercise machine and virtual (虚拟的) reality environment. Rooms have circular ceilings so astronauts will be able to watch downloaded shows and even see places on Earth, such as their homes.

    "I want to tell other kids to follow their passions." Dobek said. "Whatever they want to do they should push for it and always try their best."

    Electronic book publishing has many of the same risks and opportunities as electronic music publishing. By delivering text direct to the reader's computer screen, the e-book could cut down costs, and allow creators to deal directly with their audience, by passing (绕开) traditional publishers and traders. But it also raises the possibility of mass piracy (盗版). Phil Rance, founder and managing director of Online Originals, a London-based e-book publisher, sums it up, "No one wants Napster (在线音乐服务) to happen to books."

    Indeed, the most popular MP3may have put the frighteners on an industry that generally operates some way behind the "bleeding edge". The Meta Group, a leading US-based market researcher, says publishers are far too concerned about protecting their rights, "We believe all the recent legal control over Napster is like putting a finger in a river that is already overflowing. Publishers need to deal with reality and come up with new ways to develop wide electronic distribution, asking the question: How can we use the certainty of wide distribution to our advantage."

    At the moment, most publishers would like to limit the use of e-books to the person who bought them, or to the computer used to download them. If that can be done, e-books become just an extra income stream in a publishing industry that would continue to operate the way it does today, according to Terry Robinson, business manager for Adobe's e-paper group. "If you've cracked the digital rights aspect, you've cracked the market." He says.

    Robert Nichols, Books Director at BOL agrees, "Rights management is absolutely important. Publishers just say that 'until copyright is secure, we are not going to talk'."