The United States is a country of immigrants. It is a place where people from all over the world come to build a better life. Some immigrants bring their families. Some bring a few of their favorite things. Others come alone with nothing but determination. One thing that every immigrant brings with them is their culture.

    American immigration began in 1607 with the colony (殖民地) of Jamestown. In 1620, another group of people left England to build a settlement in America. They wanted to go to a place where they could practice their religion freely. Then many more people left their homes in Europe to build a better life in America. Many also came to America from Africa. By 1770, more than two million people had moved to America. Later on, more people came to the United States than ever before.

    In cities all over America, you can see different cultures that formed this country. Many things that you may think of as being “American” are actually from a foreign culture. Some of the best examples of this are the foods people eat. Pizza and spaghetti are foods that all Americans know and love. But both of them are from Italy. Baseball is an all-American sport. But the hot dogs that people eat during the game are a type of food that was brought to America by German immigrants.

    Over time, pizza and hot dogs have become a part of what is considered to be American food. In the same way, different groups of people have come together to define what an American is. An American can be a person of any background. An American can be of any faith. An American can be of any skin color. They can speak English clearly. They can speak English with an accent. Each new immigrant adds something new to American culture. It will keep changing as more people come to this country.

    Grown-ups are often surprised by how well they remember something they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as ever when he gets back in the water. He can get on a bicycle after many years and still ride away. He can play catch and hit a ball as well as his son. A mother who has not thought about the words for years can teach her daughter the poem that begins "Twinkle, twinkle, little star" or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, additional learning trials increase the length of time we will remember it.

    In childhood we usually continue to practice such skills as swimming, bicycle riding, and playing baseball long after we have learned them. We continue to listen to and remind ourselves of words such as "Twinkle, twinkle, little star" and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables(乘法口诀表) are an exception to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in childhood. The law of overlearning explains why cramming (突击学习) for an examination, though it may result in a passing grade, is not a satisfactory way to learn a college course. By cramming, a student may learn the subject well enough to get by on the examination, but he is likely soon to forget almost everything he learned. A little overlearning, on the other hand, is really necessary for one's future development.

    Obama, Lady Gaga and Steve Jobs—what do they have in common? They are, of course, all Americans. And according to a survey by social networking site baidu. com, they all best illustrate(举例说明) the word “cool”.

    But just what does it mean to say someone is “cool”? Most would answer that it is something to do with being independent-minded and not following the crowd.

    Yale University art professor Robert Farris Thompson says that the term “cool” goes back to 15th century West African philosophy. “Cool” relates to ideas of grace under pressure.

    “In Africa,” he writes, “coolness is a positive quality which combines calmness, silence, and life.”

    The modern idea of “cool” developed largely in the US in the period after World War II. “Post-war 'cool' was in part an expression of war-weariness (厌战情绪), . . . it went against the strict social rules of the time,” write sociologists Dick Pountain and David Robins in Cool Rules: Anatomy of an Attitude.

    But it was the American actor James Dean who became the symbol for “cool” in the hugely successful 1955 movie Rebel without a Cause. Dean plays a tough guy who disobeys his parents and the authorities. He always gets the girl, smokes cigarettes, wears a leather jacket and beats up bullies. In the movie, Dean showed what “cool” would mean to American young people for the next 60 years.

    Today the focus of “cool” has changed to athletics (体育运动) stars. Often in movies about schools, students gain popularity on the athletics field more than in the classroom. This can be seen quite clearly in movies like Varsity Blues and John Tucker Must Die.

    But many teenagers also think being smart is cool. Chess and other thinking games have been becoming more popular in schools.

    “Call it the Harry Potterization of America—a time when being smart is the new cool,” writes journalist Joe Sunnen.

    Experience around food is about the place. The time and the people, and “the best meal” can be found in a fine dining restaurant or in a crowded street market. How can you recreate that special moment influenced by place and time? Travel is becoming the most popular reason to visit many places around the world. Here are the places that consistently excite the senses.

    South of France

    Markets with fresh fruits and vegetables and butcher shops are abundant. Regional(地区的)wines are excellent. And freshly baked French bread with French butter is what memories are made of. Take a chair in an ancient walled city for a meal with a view that you will never forget.

    Barcelona

    This bustling city filled with unique buildings is a city for lovers of history, architecture, and food. Kiosko Universal, a counter restaurant at one comer of the market, prepares some of the simplest and best food we've ever had. Give yourself a week to explore and see everything the city offers. The city is not to be missed.

    Italy

    It's hard to choose one place or city to visit. Some of our favorite places include the coastal regions on the Adriatic and Tuscany. Friuli stole our hearts last year with its many unique wines, small artisan food producers, and influences fro neighboring countries like Austria and Germany.

    Mexico City

    From unbelievable food markets and casual street stands, Mexico City has become the place to travel for the food lovers. If you want to eat locally, order a Hurache, a street food specialty. All you will need is a local microbrew or Mezcal(龙舌兰酒)to wash it down.

    If you are looking for something fun and educational to do in Maryland, why not visit the Maryland Science Center? It is located at 601 Light Street, Baltimore, MD 21230.The ticket prices vary depending on ages, groups and the exhibits you choose.

    Introduction

    The Maryland Science Center is basically a museum, but it gives everyone a chance to learn through experience and play, rather than just glance at an exhibit.

    Activities

    You can learn about various topics, including outer space, the human body, dinosaurs, electricity, marine（海洋的）biology, energy, and much more. You can also take part in the interactive activities, such as racing bubbles, digging for dinosaur fossils, using puzzle pieces to construct cars, and so much more.

    The Davis Planetarium（天文馆）

    At the Davis Planetarium, you can lie back in a chair and look at the stars while still inside the Science Center. The stars will appear on the ceiling of the theatre as you watch them.

    There are different shows to catch at the Davis Planetarium. You can learn about the galaxy and astronomy during the Dark Matters show. Learn about the stars and planets during the Sky Live show. The One World One Sky show allows children to explore the stars. The Live from the Sun show will teach you all about the hot sun.

    The Kids Room

    For children, they can't miss the Kids Room. They will be able to play in a water area, construct dams and water towers, push buttons, ring doorbells, build with blocks, and more, and definitely they will learn a lot. In addition, there is also an area for kids of two years old and under, where they can crawl, walk and explore safely with soft toys.

    It is popular to travel by bike in China. China has a huge population. And it is said that there is at least one bike for every two people. Of course, many people in China ride bikes for sport or exercise, but it is also a much more commonly accepted means of everyday transportation, as compared to countries such as the United States.

    If you are living for a long time in China, chances are that you will want to buy your own bike so that you can use it whenever you want. Even if you don't use a bike for everyday transportation, owning one can be a great way to enjoy the sights in the countryside. However, if you are just visiting China, renting a bike can be a more convenient choice.

    It is important to choose the correct bike for your use. You will find that in China, the one-speed style of bike is popular. These bikes are great if you want to ride around in the city to see the sights. They are quite comfortable and easy to ride. You can often rent a bike for a day for about 15 dollars.

    However, if you wish to ride on some of the rural paths, a mountain bike style would be a better choice. They are great for different kinds of road surfaces, providing for a safer ride. If you are planning to have a wish to tour and still be able to carry packages with you, then a touring bike would be the best choice. These are the most expensive to rent, but are very suitable for carrying packages and even some of your luggage along with you.