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.

    On a stormy day last August, Tim heard some shouting. Looking out to the sea carefully, he saw a couple of kids in a rowboat were being pulled out to sea.

Two 12-year-old boys, Christian and Jack, rowed out a boat to search a football. Once they'd rowed beyond the calm waters, a beach umbrella tied to the boat caught the wind and pulled the boat into open water. The pair panicked and tried to row back to shore. But they were no match foritand the boat was out of control.

    Tim knew it would soon be swallowed by the waves.

“Everything went quiet in my head,” Tim recalls（回忆）. “I'm trying to figure out how to swim to the boys in a straight line.”

    Tim took off his clothes and jumped into the water. Every 500 yards or so, he raised his head to judge his progress. “At one point, I considered turning back,” he says. “I wondered if I was putting my life at risk.” After 30 minutes of struggling, he was close enough to yell to the boys, “Take down the umbrella!”

    Christian made much effort to take down the umbrella. Then Tim was able to catch up and climb aboard the boat. He took over rowing, but the waves were almost too strong for him.

“Let's aim for the pier（码头）,” Jack said. Tim turned the boat toward it. Soon afterward, waves crashed over the boat, and it began to sink. “Can you guys swim?” he cried. “A little bit,” the boys said.

Once they were in the water, Tim decided it would be safer and faster for him to pull the boys toward the pier. Christian and Jack were wearing life jackets and floated on their backs. Tim swam toward land as water washed over the boys' faces.

    “Are we almost there?” they asked again and again. “Yes,” Tim told them each time.

    After 30 minutes, they reached the pier.

    I have received many Christmas gifts over the years. The best gift I ever received was presented to me by a stranger. I never even knew his name and I only had contact with him for less than 60 seconds. His Christmas present to me changed the way I had thought about people and Christmas.

    It was several years ago when my wife asked me to meet her at the local department store on Black Friday morning. They had advertised a child's bike that she wanted to purchase for our son. We stood with a very large crowd, waiting for the manager to blow the whistle. After a while, the whistle blew. It was like throwing a bucket of fish into a tank of sharks. I told my wife that if we obtained a bike, fine, but we did not, I was OK with that too,

    As the shelf of bikes began to gradually decrease in size, I saw my polite opportunity to wrap my hands around the corner of one of the boxes. I lifted it off the box and suddenly felt some mild resistance. I looked up to see one of the largest gentlemen I had ever seen in my life. Threat was not the word to describe his presence. He was decorated with numerous belts of metal pointed leather around both arms and even his neck. Tattoos(文身) were an obvious passion of his.

    I started to return anxiously the box but he gently pushed it back in my direction and back into my hands. He then directed it into my shopping cart. He look d at me, smiled, and said, “Merry Christmas. ”My wife and I went to the checkout, paid for the bike and went home. All the way home I was thinking that this moment was by far the best Christmas gift I had ever received. The kindness of a stranger that broke all previous views I may have had of stereotypes and prejudices. I will never forget the tenderness of a human heart in a simple act.

    Minecraft, a video game with which you can build virtual（虚拟的） worlds, will be used in the classroom. Microsoft bought the game from its Swedish creator for 2.5 billion dollars. Now, the software（软件） company wants to offer schools a special educational version（版本）.

    MinecraftEdu is an add-on to the game, which has specially created by teachers for classroom use. While thousands of classes around the world are already using Minecraft in their lessons, Microsoft wants to make it easier for schools to use the software.

    Minecraft is a game that can be used in many subjects, including maths, science and geography. Microsoft wants to add new features to the educational version, for example letting students take photos and putting them into an online diary. The new version will allow children to download the game and at home without having to pay more money for it. Microsoft is expected to ask students and teachers for about 5 dollars a year to use the game in school and at home.

    According to Microsoft, Minecraft has 100 million players around the world. It has become one of the best-selling games of all times. Pupils can create their own virtual worlds with the help of special building blocks. Joy Morsi, a New York high school teacher, says that Minecraft helps develop the imagination of children in the classroom. Besides, teachers around the world create new things and share them with others, so that the Minecraft community keeps growing.

    Microsoft plans to make the game of available to pupils and students of all ages, from primary school through to college. the company plans to add Minecraft to an Office 365 account(账户), so that it can also sell more of its Office software.

    The Eiffel Tower is very famous in France. It is visited by 7 million visitors a year. The Eiffel Tower was designed by Gustave Eiffel in the late 19th century. On Monday, March 31st, 2019, it turned 130.

    The look of the Eiffel Tower is greatly loved by people today, but things were different when the design was first shown to the public. Many French artists thought that the design was ugly. However, Eiffel did not change a thing. He believed that once it was completed, people in Paris and visitors around the world would love the tower. He was certainly right.

    The tower became popular with the public as soon as it opened on March 31st, 1889, two years after the construction began. Over 3,000 people came to look at this new tower and even made the effort to climb the 1,710 stairs to the top. The 984-foot-tall Chrysler Building in New York City beat it.

    Today, the tower houses a number of restaurants on its first and second levels. The third level has been turned into a vast platform (平台). From there visitors can see the entire city of Paris. While visitors are allowed to take the stairs to the first two levels, the platform can only be got to by taking the elevators.

    To ensure that the “Iron Lady” always looks good, the tower is cleaned and repainted every eight years. It's an effort that takes a team of 25 workers, an entire year. If you travel to Paris one day, don't miss it, the excellent achievement.

    Jim Denevan is an amazing artist whose work is admired by all, but owned by none — that's because all of Jim's art is created on an unusual canvas(画布)— the soft sand. He sometimes spends days working on a piece, only to see it washed away by the sea or a storm and that is just the way he likes it.

    Denevan discovered his artistic talents about ten years ago, when he was wandering aimlessly on the beach with a stick. He ended up drawing a 12-foot-long fish. Since then, Jim has traveled over 1,800 miles while creating over 600 pieces of sand art.

    Over the years, his drawings have become bigger, but the tools he uses haven't changed — All he needs is a stick, a garden rake (耙子)and most importantly, his lively imagination!

    Just like any good artist, Jim is quite particular about the "quality" of his canvas, sometimes walking for miles, looking for perfect sand. His latest piece of work, which is also the world's largest freelance (自由职业的)drawing, was created in the desert sand of Nevada. It took Jim three trips, eight days and over 100 miles of walking to create this 3-mile work of art. It took the storm just one night to destroy it! However, Jim says he actually enjoys watching the waves or rain, wash his paintings away.

    Jim's art has become very popular over the years and was even the topic of a documentary named "Sandman" in 2015. Jim Denevan is not just about art in the sand — he is also an excellent chef and founder of an organization called "Outstanding in the Field", whose mottois to celebrate food at its source. Accordingly, group dining events are held outdoors on farms, with the diners being treated to a delicious meal. The events, which are held in different farms throughout America, are always sold out the minute the schedule is announced.