The morning had been a disaster. My tooth was aching, and I'd been in an argument with a friend. Her words still hurt: “The trouble with you is that you won't put yourself in my place. Can't you see things from my point of view?” I shook my head stubbornly—and felt the ache in my tooth. I'd thought I could hold out till my dentist came back from holiday, but the pain was really unbearable. I started calling the dentists in the phone book, but no one could see me immediately. Finally, at about lunchtime, I got lucky.

    “If you come by right now,” the receptionist said, “the dentist will fit you in.”

    I took my purse and keys and rushed to my car. But suddenly I began to doubt about the dentist. What kind of dentist would be so eager to treat someone at such short time? Why wasn't he as busy as the others?

    In the dentist's office, I sat down and looked around. I saw nothing but the bare walls and I became even more worried. The assistant noticed my nervousness and placed her warm hand over my ice-cold one.

    When I told her my fears, she laughed and said, “Don't worry. The dentist is very good.”

    “How long do I have to wait for him?” I asked impatiently.

    “Come on, he is coming. Just lie down and relax. And enjoy the artwork,” the assistant said.

    “The artwork?” I was puzzled.

    The chair went back, suddenly I smiled. There was a beautiful picture, right where I could enjoy it: on the ceiling. How considerate the dentist was! At that moment, I began to understand what my friend meant by her words.

    What a relief！

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    Navajo was the perfect choice for a secret language. It is very complex. One vowel (元音）can have up to ten different pronunciations, changing the meaning of any word. In the 1940s, Navajo was unwritten language. No one outside of the reservation could speak it or understand it.

    The Navajo Code team had to invent new words to describe military equipment. For example, they named ships after fish: lotso-whale (battleship), calo-shark (destroyer), beshloiron-fish (submarine). When a Code Talker received a message via radio, he heard a series of unrelated Navajo words. He would then translate the words into English and use the first letter of each English word to spell the message. The Navajo words tsah (needle), wol-la-chee (ant), ah-kh-di-glini (victor), and tsah-ah-dzoh (yucca) spelled NAVY.

    The Code Talker kept the code a secret. They memorized everything. There were no code books. As a result, no ordinary Navajo soldiers, if captured by the enemy, could understand the code. More than 3,600 Navajos served in World War II, but only 420 were Code Talkers with the US Marines. They coded and decoded battlefield messages better and faster than any machine. They could encode, transmit, and decode a three-line English message in 20 seconds. Machines of the time required 30 minutes to perform the same job.

    Even after the war the code remained top secret. When they were asked about their role, Code Talkers just said: “I was a radioman.” War movies and histories came out without mentioning them. The code was never used again and was finally declassified in 1968. Only then did the secret came out.

    Children who do better than their companions at school tend to go on to enjoy better health as adults, research suggests. The study was based on a 30-year follow-up of more than 14.000 children born in Sweden in 1953.

    The Journal of Epidemiology and Community Health study found the least popular children had a nine times higher risk of heart disease. They were also more at risk of diabetes (糖尿病),drugs, alcohol and mental health problems.

    The degree of popularity, power and status enjoyed by each child, was evaluated when the children reached sixth grade in 1966 by asking them who they most preferred to work with at school. Individual children were classified into five status bands depending on how many nominations (提名) they have received.

    The leader researcher Ylva Almquist, from the Center for Health Equity Studies at the University of Stockholm, said children with a low status might lack social support and information, this will lead to a more negative self-image, which could lead to lower expectations and poor choices in life.

    “For example, children in lower peer status may adopt a more health-damaging lifestyle, including behaviors such as heavy smoking and drinking. These behaviors are known to be major risk for heart disease.” she said.

    She said the study shows that schools should work to promote social equality in the classroom, and to improve children's self-image.

    Professor Alan Maryon-Davis, president of the UK Faculty of Public Health, said, “Children who feel undervalued or are bullied (欺凌) at school often grow up lacking self-confidence. They then seek comfort in overeating, smoking or drinking, and all too often find themselves in poor health. It is important to do whatever we can to help children and young people feel valued.”

    When most of us look at our hands, we might notice that we need to clean, or stop biting our fingernails, and that's about it. But if you ask a doctor, he can see a whole lot more. Everything from poor diet and stress to serious kidney (肾) problems can be revealed by a glance at your fingernails.

    There are about 30 different nail signs that can be associated with medical issues, though may indicate more than one problem, according to Dr. Amy Derick, a clinical instructor of dermatology at Northwestern University.

    Here are five of the things a doctor can tell about your health based on your fingernails.

    ⒈People who aren't eating well and lack vitamin or dietary may have thinner than normal nails, which are more likely to break.

    ⒉Horizontal lines are associated with serious physical stress. They frequently occur in people who have gone through chemotherapy(化疗).They can also occur after some illnesses, injuries, or with severe malnourishment(营养不良).Interestingly, there may be an altitude connection too. They've also been found in people who dove 1,000 feet and others who participated in an Everest exploration.

    ⒊Vertical lines, however, are generally not such a big deal. Some people are more genetically prone to them than others, but they're commonly associated with aging.

    ⒋When people lack iron, their nails can turn spoon-like. Instead of curving down and covering the finger normally, they'll start to rise up on the sides and front, like the part of a spoon that holds liquid.

    ⒌Kidney and liver problems can create “half-and-half nails”, where one part of the nail is white and the other part dark or pink, according to Derick.

    Doctors note that because disease diagnosis is complex and some symptoms can be associated with different diseases, you should always see a medical professional if you are concerned about something you notice.

    We bet that on cold winter days, many of you love to stay in your warm home and, every now and then, come out into the kitchen for a snack. Unfortunately, plenty of small insects like to do the same thing! Winter is the time when small insects enter your house without an invitation. The season can be difficult for such creatures. In winter the air is cold, the ground is hard and many trees have no leaves. So small insects do what they have to do to survive.

    Monarch butterflies head south to warmer climates. Ants crowd in deep underground colonies and eat food they have been storing all year. Many insects go into a deep sleep called diapauses. There're different kinds of diapauses, but all are similar to hibernation, a time when bigger animals become inactive in the cold. Insects go into an inactive period, too, but it often isn't when the temperature drops.

    They rely on more dependable signals in the environment. For example, many insects can tell how much sunlight there's each day. They use that to tell themselves when to shut down. Insects are cold-blooded, meaning that their inside temperature is the same as the outside. They can't move much when it gets below 40 degrees Fahrenheit. So they search for any warm place.

    They're looking for protection. These guys have been doing this for 300 million years, so they don't really know they're coming into your house. The home is a recent event in terms of their evolutionary (进化的) behavior. They enter through tiny cracks or come in unnoticed on your clothes or shoes. Remember that they may be entering your homes for warmth and food, but they don't care about humans.

    There are some very good things about open education. This way of teaching allows the students to grow as people, and to develop their own interests in many subjects. Open education allows students to be responsible for their own education, as they are responsible for what they do in life. Some students do badly in a traditional classroom. The open classroom may allow them to enjoy learning. Some students will be happier in an open education school. They will not have to worry about grades or rules. For students who worry about these things a lot, it is a good idea to be in an open classroom.

    But many students will not do well in an open classroom. For some students, there are too few rules. These students will do little in school. They will not make good use of open education. Because open education is so different from traditional education, these students may have a problem getting used to making so many choices. For many students it is important to have some rules in the classroom. They worry about the rules even when there are no rules. Even a few rules will help this kind of students. The last point about open education is that some traditional teachers do not like it. Many teachers do not believe in open education. Teachers who want to have an open classroom may have many problems at their schools.

    You now know what open education is. Some of its good points and bad points have been explained. You may have your own opinion about open education. The writer thinks that open education is a good idea, but only in theory. In actual fact, it may not work very well in a real class or school. The writer believes that most students, but of course not all students, want some structure in their classes. They want and need to have rules. In some cases, they must be made to study some subjects. Many students are pleased to find subjects they have to study interesting. They would not study those subjects if they did not have to.