The concept of culture has been defined many times, and although no definition has achieved universal acceptance, most of the definitions include three central ideas: that culture is passed on from generation to generation, that a culture represents a ready-made principle for living and for making day-to-day decisions, and, finally, that the components of a culture are accepted by those in the culture as good, and true, and not to be questioned. The eminent anthropologist George Murdock has listed seventy-three items that characterize every known culture, past and present.

    The list begins with Age-grading and Athletic sports, runs to Weaning and Weather Control, and includes on the way such items as Calendar, Fire making, Property Rights, and Tool making. I would submit that even the most extreme advocate of a culture of poverty viewpoint would readily acknowledge that, with respect to almost all of these items, every American, beyond the first generation immigrant, regardless of race or class, is a member of a common culture. We all share pretty much the same sports. Maybe poor kids don't know how to play polo, and rich kids don't spend time with stickball, but we all know baseball, football, and basketball. Despite some misguided efforts to raise minor dialects to the status of separate  tongues, we all, in fact, share the same language.

    There may be differences in diction and usage, but it would be ridiculous to say that all Americans don't speak English. We have the calendar, the law, and large numbers of other cultural items in common. It may well be true that on a few of the seventy-three items there are minor variations between classes, but these kinds of things are really slight variations on a common theme.

    There are other items that show variability, not in relation to class, but in relation to religion and ethnic background — funeral customs and cooking, for example. But if there is one place in America where the melting pot is a reality, it is on the kitchen stove; in the course of one month, half the readers of this sentence have probably eaten pizza, hot pastrami, and chow mein. Specific differences that might be identified as signs of separate cultural identity are relatively insignificant within the general unity of American life; they are cultural commas and semicolons in the paragraphs and pages of American life.

    Tourism wasn't as important as it is today. In the past, only people with a good deal of money could travel on holidays to other countries. More people travel today than in the past because there is a growing middle class in many parts of the world; that is to say, people now have more money for travel. Special plane fares(费用) for tourists make travel less expensive and more attractive than ever before. One person doesn't travel for the same reason as another. But most people enjoy seeing countries that are different from their own. They also like to meet new people and to taste new food.

    Tourism causes many changes in a country and in people's lives. People build new hotels and restaurants and train native men and women as guides to show visitors interesting places. There're new nightclubs and other amusements. International tourism is clearly a big business.

    My friend, Jack, was a taxi driver. We became friends quite by accident. Five years ago, I made a trip to Chicago. The moment I stepped into a cab, I realized it was different. The floor was covered with a rug (小地毯). There were small reproductions of paintings by Van Gogh inside the cab. And the windows were spotless. I told the driver I had never ridden in a more attractive taxi.

    "I like to hear my passengers say that," he replied. "How long have you been decorating your cab?" I asked. "It's not mine," he said. "It's a company cab. I hit upon the idea years ago when I worked as a clean-up man for the taxi company. Each car that came in at the end of the day was like a garbage pit. Cigarette butts and matches covered the floor. Sticky stuff like peanut butter was on the seats or door handles. I thought that if the company and the drivers would give people a car worth keeping clean, they might be more considerate."

    "As soon as I got my taxi license, I tried out my ideas. I put a lot of extra decorations into the cab they gave me to drive. I got a nice rug and some flowers. When each passenger got out, I checked to make sure that everything was in order for the next fare. After about a month of my bringing in a spotless cab, the boss reserved the same car for me each day. That was when I put up the reproductions of great paintings."

    "I've never been disappointed by people in the past ten years—no garbage. Like I say, people appreciate beautiful things. If we planted more flowers and trees in the city and made the buildings more attractive, more people would tend to keep the city clean."

    Later, we became good friends. I was impressed by the taxi-driver, who had hit on a great truth—a sense of beauty comes with the gift of life. Most people don't have to be instructed about the rarity of beauty. They respond when they find it. And, if they are made to feel a part of it, they will try to add to it.

    When your dream is to become a footballer, nothing should get in your way—even if you have no feet.

    Gabriel Muniz, an 11-year-old Brazil kid, was born without feet. Although his family thought he would have serious difficulties living a normal life, he started walking before he was one year old. His mother would go after him, expecting him to keep falling, but he never fell. It took him a while to make the jump from walking to playing football, but he did make it. And, in fact, there's nothing he loves more than playing football. In his school, the skillful youngster (年轻人) is not only the best player in his school team but also the captain of his gym team.

    He knows that his disability means he'll never be able to play for a professional (专业的) football team. So Gabriel is hoping that football will one day become a Paralympics (残疾人奥运会的) sport. He proved to everyone there he could go head to head with any other boy. Watching him play is unbelievable. He's fast and he's got a big bag of tricks—he's very skilled and he does everything he can to copy his hero, Messi so much that he is invited to go to Spain to meet his hero Messi and show his talent in the Barcelona Football Club.

    His coach says he is proving the disability only exists (存在) inside our heads.

    I was driving my newly acquired motorcycle across the vastness of North Dakota when all of the sudden it froze up on the road. I would later be told the belt had slipped and this caused one of the pistons(活塞)to break a cylinder(气缸)head, or something like that.

    Anyway, I sat on the side of the road for what seemed like hours. I even pretended to have been in an accident, which didn't help. Finally, a young man pulled over and offered me a ride, but given that he already had two motorcycles in the back of his truck, he could only take me.

    He drove me to the next town, where I asked to be dropped off Rather than drop me off, he waited while I asked around if anyone could help me to pick up my motorcycle. One elderly gentleman was working and said that I could use his pickup! Can you imagine that a stranger gave me the keys to his pick up. It was quite an experience, I must say. So, as I drove back 20 miles to get my motorcycle, the gentleman who first stopped to help me followed me. We both put the motorcycle in the back of the truck and then I followed him another 50 miles or so and we both unloaded the motorcycle at his place. Then, he followed me back to the small town so I could return the man's truck. I didn't have much cash on me, maybe $40, but I gave it to the man for the use of his truck.

    Two strangers helped rescue me from spending the night on the side of the road in ND. I don't recall their names, but when I close my eyes I can see their faces as if it were yesterday. Thank you, strangers. You may be reading this right now.

The periodic table of elements is a common sight in classrooms，campus hallways and libraries. The mode periodic table arranges the elements by their atomic numbers and periodic properties（周期性）. Several scientists worked over a century to assemble the elements into this format. 

In 1789，French chemist Antoine Lavoisiertried grouping the elements as metals and nonmetals. Forty years later，German physicist Johann Wolfgang Dobereiner observed similarities in physical and chemical properties of certain elements. He arranged them in groups of three in increasing order of atomic weight and called them triads，observing that some properties of the middle element，such as atomic weight and density，approximated the average value of these properties in the other two in each triad. 

A breakthrough came with the pu blication of a revised list of elements and their atomic masses at the first international conference of chemistry in Karlsruhe，Germany，in 1860. They concluded hydrogen would be assigned the atomic weight of 1 and that the atomic weight of other elements would be decided by comparison with hydrogen. For example，carbon，being 12 times heavier than hydrogen，would have an atomic weight of 12. 

In 1869，Russian chemist Dmitri Mendeleev created the framework that became the moder periodic table，leaving gaps for elements that were yet to be discovered. Mendeleev predicted the properties of some undiscovered elements and gave them names such as"eka-aluminum"for an element with properties similar to aluminum. Later "eka-aluminum"was discovered as gallium. 

German chemist Lothar Meyer produced a version of the periodic table similar to Mendeleev's in 1870. He left gaps for undiscovered elements but never predicted their properties. The Royal Society of London awarded the Davy Medal in 1882 to both Mendeleev and Meyer. The later discovery of elements predicted by Mendeleev verified（证实）his predictions and his periodic table won universal recognition. In 1955 the 101st element was named mendelevium in his honor. 

On UNESCO website，it wrote，"The Periodic Table of Chemical Elements is more than just a guide or catalogue of the entire known atoms in the universe；it is essentially a window on the universe，helping to expand our understanding of the world around us. "