It is bad to have food stuck between your teeth for long periods of time. This is because food attracts germs; germs produce acid, and acid hurts your teeth and gums. Flossing (使用牙线) helps to remove the food that gets stuck between your teeth. This explains why flossing helps to keep your mouth healthy, but some doctors say that flossing can also be good for your heart.

    It may seem strange that something you do for your teeth can have any effect on your heart. Doctors have come up with a few ideas about how flossing works to keep your heart healthy. One idea is that the germs that hurt your teeth can leave the mouth and travel into your blood.Germs that get into the blood can then attack your heart. Another idea is based on the fact that when there are too many germs in your mouth, the body tries to fight against there germs. For some reason, the way the body fights these mouth germs may end up weakening the heart overtime.

    Not every doctor agrees about these ideas. Some doctors think that the link between good flossing habits and good heart health is only a coincidence. The incidence (发生率) of two or more events is completely random, as they do not admit of any reliable cause and effect relationship between them. For example, every time I wash my car, it rains. This does not mean that when I wash my car, I somehow change the weather. This is only a coincidence. Similarly, some doctors think that people who have bad flossing habits just happen to also have heart problems, and people who have good flossing habits just happen to have healthy hearts.

    The theory that flossing your teeth helps to keep your heart healthy might not be true. But every doctor agrees that flossing is a great way to keep your teeth healthy. So even if flossing does not help your heart, it is true to help your teeth. This is enough of a reason for everyone to floss their teeth every day.

    See a cellphone cover that you like on Taobao? Forget about placing an order, paying the bill online and waiting for days for it to be delivered to you. In the near future, you'll be able to get it in minutes just by hitting “print” on your computer.

    You might find it hard to believe that you could actually “print” an object like you would a picture. But it is not that hard to understand how it would work. Just as a traditional printer sprays ink onto paper line by line, modern 3D printers spread material onto a surface layer by layer, from the bottom to the top, gradually building up a shape.

    Instead of ink, the materials the 3D printer uses are mainly plastic, resin(树脂) and certain metals. The thinner each layer is—from a millimetre to less than the width of a hair—the smoother and finer the object will be.

    This may sound like a completely new technology, but the truth is that 3D printing has been around since the late 1980s. Back then, it was barely affordable for most people, so few knew about it.

    Last year, though, saw a big change in the 3D printing industry—printers became much cheaper. For example, 10 years ago a desktop 3D printer might have cost ￡20，000, while now they cost only about ￡1，000, according to the BBC.

    Taken out of the factory and introduced to more diverse and common uses, 3D printing can create just about anything you can think of—flutes , bikinis, jewelry, aircraft parts and even human organs. In fact, scientists from Cornell University in New York have just made an artificial ear using a 3D printer, according to Science Daily. The fake ear looks and acts exactly like a natural one.

    However, as 3D printing becomes more common, it may bring about certain problems—such as piracy. “Once you can download a coffee maker, or print out a new set of kitchen utensils (餐具) on your personal 3D printer, who will visit a retail  store again？” an expert in 3D printing told Forbes News. Even more frightening, what if anyone in the world could use a 3D printer to print out a fully functioning gun?

    SPECIAL EVENTS THIS WEEKEND

Captain Good Fellow

    Do your children enjoy interesting stories, funny games, and exciting dances? Captain Good Fellow will be ready to teach all these things to children of all ages at the City Theatre on Saturday morning at 10:00. Free.

Walking Tour of the Town

    Forget your worries on Saturday morning. Take a beautiful walk and learn about local history. Meet at the front entrance of City Hall at 9:30. Wear comfortable shoes!

Films at the Museum

    Two European films will be shown on Saturday afternoon at the Museum Theatre. See Broken Window at 1:30. The workers will be at 3:45. For further information, call 4987898.

International Picnic

    Are you tired of eating the same food every day? Come to Central Park on Saturday and enjoy food from all over the world. Delicious and not expensive. Noon to 5:00 pm.

Take Me out to the Ballgame

    It's October, and tonight is your last chance to see the Redbirds this year. Get your tickets at the gate. It might be cold; don't forget sweaters and jackets.

Do You Want to Hear “The Zoo”

    “The Zoo”, a popular rock group from Australia, will give their first US concert tomorrow night at 8:00 at Rose Hall, City College.

    Guide to Stockholm University Library

    Our library offers different types of studying places and provides a good studying environment.

    Zones

    The library is divided into different zones. The upper floor is a quiet zone with over a thousand places for silent reading, and places where you can sit and work with your own computer. The reading places consist mostly of tables and chairs. The ground floor is the zone where you can talk. Here you can find sofas and armchairs for group work.

    Computers

    You can use your own computer to connect to the wifi specially prepared for notebook computers; you can also use library computers, which contain the most commonly used applications, such as Microsoft Office. They are situated in the area known as the Experimental Field on the ground floor.

    Group-study Places

    If you want to discuss freely without disturbing others, you can book a study room or sit at a table on the ground floor. Some study rooms are for 2-3 people and others can hold up to 6-8 people. All rooms are marked on the library maps.

    There are 40 group-study rooms that must be booked via the website. To book, you need an active University account and a valid University card. You can use a room three hours per day, nine hours at most per week.

    Storage of study material

    The library has lockers for students to store course literature. When you have obtained at least 40 credits(学分), you may rent a locker and pay 400 SEK for a year's rental period.

    Rules to be followed

    Mobile phone conversations are not permitted anywhere in the library. Keep your phone on silent as if you were in a lecture and exit the library if you need to receive calls.

    Please note that food and fruit are forbidden in the library, but you are allowed to have drinks and sweets with you.

    Cheating is nothing new. But it's becoming a lot more sophisticated. Republican vice-presidential candidate Sarah Palin was caught out once. A photo taken after the speech she'd given on a "return to conservative principles" showed her left hand covered with crib notes. These included the words "energy, budget cuts, tax" and "lift Americans' spirits". The word "budget" had been crossed out. Video footage also showed her reading from her hand when asked what top three things a conservative-led congress should do. Writing notes on your hand is one way to cheat in an exam. But these days, it's a lot easier ... especially with the Internet.

    Anyone who wants to cheat in an exam can probably find the answers online. There are hundreds of sites offering solutions to all sorts of tests. And it's a lucrative business. One operator in Oregon made $700,000 in about nine months before his arrest. The owner of a website in Ohio pocketed more than $300,000. And a famous overseas site is estimated to sell about 146,000 sets of answers and take in about $10 million per year. Actually, getting hold of the exam answers isn't that hard. Some do the exam themselves and use button cameras or document-scanning pens to copy the tests. Others organize for a group to take tests repeatedly until they can memorize the entire exam between them. Others simply bribe exam administrators.

    At the moment, such business is booming. More and more companies now require their employees to take professional exams. And hundreds of businesses and trade organizations have introduced formal certification programs to measure employee skills. In the US alone, at least 2 million exams are taken every year for information technology certification. But employees also have to take exams for all sorts of professions from crane operators to court reporters to school bus drivers and financial planners. Test officials estimate that hundreds of thousands of test-takers have used the Internet to buy answers for professional tests. And a recent survey found that 28 percent of test centres had at least one cheating incident over the last five years. In one incident, tens of thousands of soldiers obtained answers to tests in a range of military skills.

    Many see this as a cause for concern. Many tests are for work in sensitive areas such as defence installations and hospitals. Now, how would you feel if you knew that the people in charge of the computers controlling nuclear weapons might have cheated in their tests, and may not really know what they're doing?

    On a recent afternoon, some 60 years after they graduated from grammar school, Kathleen Rys, 72, and her sister Lorraine O'Kelly, 70, sat down and had a meal with a classmate, Bruce Smit, 71 for the first time.

    In the 1950s, Lorraine and Kathleen Rys' family moved from Chicago to Monee. As new kids at Monee Elementary School, they soon found themselves on the outs with other students.

    "I would be with the other guys and see Kathleen walking down the hallway, her head down, holding her books, walking slowly. And all of us guys would be flat against the wall until she passed. Then we'd burst into laughter. How rude is that? It's just crazy." said Smit, a doctor whose wife, Tammy, organized the meeting.

    The women said none of the teachers cared about it. "We just kept it to ourselves. " Lorraine said.

    Over the years, Tammy Smit said, "Bruce would just start to cry at times. He'd wonder what happened to the sisters, if they landed OK." One day a few weeks ago, Tammy took to the internet and found Mary O'Kelly, Lorraine's daughter, and offered to set up a meeting. The idea of revisiting the pain was not well- received by Kathleen, who had never married, let alone gone on a date. It took some convincing, but Lorraine finally got Kathleen to agree to meet with Bruce.

    Bruce broke into tears. "I'm so ashamed, so embarrassed," he said. "But I'm so happy you're still here and that I can finally apologize. " He said he hopes his apology will encourage others to seek forgiveness for the pain they make on others. Lorraine said, "This is a beautiful thing. It's just wonderful that a person from 60 years ago can ask for forgiveness. It's like a miracle to us. It's a healing to us."