Now many young people are traveling around the world on their own, not because they have no one to travel with, but because they prefer to go alone．

     Kristina Wegscheider from California first traveled alone when she was at college and believes that it is something everyone should do at least once in their life. “It opens up your mind to new things and pushes you out of your comfort zone.” Wegscheider has visited 46 countries covering all seven continents(洲)．

    In foreign countries, with no one to help you read a map, look after you if you get ill, or lend you money if your wallet is stolen. It is challenging. This is what drives young people to travel alone．It is seen as character building and a chance to prove that they can make it on their own．

    Chris Richardson decided to leave his sales job in Australia to go traveling last year．He set up a website, The Aussie Nomad, to document（记录） his adventures. He said he wished he had traveled alone earlier. “The people you meet, the places you visit, or the things you do, everything is up to you and it forces you to grow as a person,” said the 30-year-old．

    Richardson describes traveling alone like “a shot in the arm”, which “makes you a more confident person that was ready to deal with anything”. He said: “The feeling of having conquered something on my own is a major part of what drives me each day when I'm dealing with a difficult task. I walk around with my head up because I know deep down inside that nothing is impossible if you try.”

    The great 19th century explorer John Muir once said: “Only by going alone in silence can one truly get into the heart of the wilderness.

    Typing with one hand when the other one is occupied can be a real pain, so imagine having to type with just one foot. It's got to be a nightmare, but 21-year-old Hu Huiyuan from China's Anhui Province is using her only functional foot to write not just a few sentences, but an entire fiction novel!

    Born prematurely(过早地), Hu was diagnosed with cerebral palsy(脑瘫) when she was only 10 months old. This left her permanently paralyzed—the only parts of her body she can move are her head and left foot. As she grew older, she learned how to perform everyday tasks using her foot.

    Despite not having received formal education, Hu is surprisingly well-spoken. Over the years, with the help of her mother, she taught herself to read and write. “I'm not a genius, but I'm very focused,” she said, modestly. “When I watched TV in my childhood, I often learned words on the screen.”

    “When I was teaching her how to speak, I had to repeat every single word a thousand times before she got it, ”Hu's mother said. “But once she mastered the word. I felt satisfied.”

    With time going by, Hu's language got so proficient that she set out to write a story about the pursuit of dreams and love. She's doing this by typing out every single word on her computer using only one foot.

    In spite of all these setbacks, Hu is able to type 20 to 30 words a minute. She has already written six chapters—that's 60,000 words—and says she only has two more chapters to go before the novel is complete.

    Language is always changing. In a society where life continues year after year with few changes, the language does not change either. The earliest known languages had difficult grammar but a small, limited vocabulary. Over the century, the grammar changed, and the vocabulary grew. For example, the English and Spanish people who came to America during the sixteenth century gave names to all the new plants and animals they found. In this way, hundreds of new words were introduced into English and Spanish vocabularies. Today life is changing very fast, and language is changing fast too.

     There are several major(主要) language families in the world. Some scientists say there are nine main families, but other scientists divide them differently. The languages in each family are connected, and scientists think that they came from the same parent language. About 3 percent of the people in the world speak languages that are not in these major families.

    It is not easy to become a doctor in the United States. The first step is getting into a medical college. More than one hundred and twenty American schools offer study programs for people wanting to be doctors.

    People can get advice about medical schools from many resources. One of these is the Princeton Review. The publication provides information about colleges, study programs and jobs.

    The Princeton Review says the competition to enter medical schools is strong. American medical schools have only about sixteen thousand of openings. But more than thirty-two thousand students may try it. Many of those are women.

    Most applicants contact more than one medical school. Some contact many. An important part of the application usually is the Medical College Admission Test which is called MCAT. The Association of American Medical Colleges provides the test by computer. It is offered in the United States and other countries.

    The people who want to enter medical schools are rated（评定）on reasoning, physical and biological sciences and an example of writing. Applicants for medical schools need to do well on the MCAT. They also need a good record in their college studies.

    Some students work for a year or two in a medical or research job before they attempt to enter a medical school.

    Two heads are better than one. After all, when trying to make decisions, it's good to have a second opinion. But what about a third, fourth — even twelfth? What group size is best for making decisions quickly? For ants, four to six heads surpass one and also outperform 12 or 24. That's what Sylvia Zamescu now reports.

    The 18-year-old senior at Catalina Foothills High School in Tucson, Arizona isn't generally into ants. She's interested in decision-making, especially by people. Last summer, Sylvia read that social insects such as ants and bees can be used to model decision-making. Ants, for example, forage for food. When an ant finds it, it takes a bite and heads back to the nest. On the way; the ant leaves a scented trail for other ants to pick up. Back at the nest, the ant vomits up its meal into the mouth of other ants. Those nest-mates then decide with the first ant whether the food is good enough to deserve a trip back for more. If it is, they follow the first ant's scented trail to lunch.

    When there are too few ants, it could take a long time for one ant to spread the word. If there are too many, it's hard to "tell" each about the find. What's the right number for foraging success? Sylvia decided to find out. She contacted professors at the University of Arizona in Tucson to look for someone who would let her study decision-making by ants in their lab. Professor Wulfila Gronenberg answered her email.

    Working with one of Wulfila's graduate students Sylvia set up an experiment. She tested the behavior of one, two, four, six, twelve and twenty-four ants. Each group was placed in a large box al taped "starting line". At the other end of the box were two bricks of sweetened gelatin (动物胶) one contained only 3 per cent sugar, and the other 30 per cent. Sylvia timed how long it took each group of ants to find the food. She also measured how much time they spent around each sweet treat.

    When there were just one or two ants, the discovery was slow. The same was true when she set twelve or twenty-four ants loose. But four to six ants? Perfect! These medium-size groups found the food forest. They also figured out quickly that the sweeter food was better.

    Similar work has been done on bighorn sheep, fish and fruit flies. "It may not be four to six animals, but it's the same principle," Sylvia says. A medium-size group "is optimal". So when faced with a new decision, two heads are better than one. But too many heads are too much. Like the ants, a good decision may just require a happy medium.