One day an ant was drinking at a small stream and fell in. She made desperate efforts to reach the side, but made no progress at all. The poor ant almost exhausted was still bravely doing her best when a dove saw her. Moved with pity, the bird threw her a blade of grass, which supported her like a raft, and thus the ant reached the bank again. While she was resting and drying herself in the grass, she heard a man come near. He was walking along barefooted with a gun in his hand. As soon as he saw the dove, he wished to kill it. He would certainly have done so, but the ant bit him in the foot just as he raised his gun to fire. He stopped to see what had bit him, and the dove immediately flew away. It was an animal much weaker and smaller than herself that had saved her life.

    Travelling around the world with children is difficult enough, while attempting it without using motorized transport is even more of challenge．Even so, Dario Schworer a 42-year-old climatologist and mountain guide, and his 33-year-old wife Sabine are on a journey to do just that．

    The Swiss couple want to travel across the world's oceans and climb the highest mountain on every continent to promote Earth-friendly ways of life．

    "We are collecting good examples of dealing with climate change and living in harmony with nature and we want to spread such ideas．" Schworer said．"We want to help people affected by global warming and to inspire children for the future．"

    Recently after having spent three months teaching children in the Everest region, the couple want to show it is possible to travel through the world's climate zones using just human-power and forces of nature．

    In the 47 countries they have visited they have collected 22 tons of trash, taught people in Ecuador how the sun's rays can be used to clean water and inspired a person in Chile to build a house on water with recycled plastic bottles as a foundation．They have also collected trash in the mountains of Nepal with school children．

    So far they have communicated with 45,000 children from South America, Australia and Asia, giving presentations about the importance of recycling and using alternative energy like solar and wind power．

    When they began their adventure in 2003 they had no children of their own．But since then two has become five: daughter Sabine is now five years old, Andri was born in Chile and baby Neo was born in Australia．

    Initially the couple thought they would complete their travels in four years, but now, they believe it could take seven more．

    "Since our belief is the need to respect nature, we travel only when conditions are good," Schworer said．

    A little old couple walked slowly into McDonald's one cold winter evening. They were so old that they looked out of place among the young families and young couples eating there that night.

    Some of the customers looked admiringly at them. You could tell what the admirers were thinking. “Look, there is a couple who has been through a lot together, probably for 60 years or more!”

    The little old man walked right up to the cash register (收银台), placed his order with no hesitation and then paid for their meal. The couple took a table near the back wall and started taking food off the tray (托盘). There was one hamburger, one order of French fries and one drink. The little old man unwrapped the plain hamburger and carefully cut it in half. He placed one half in front of his wife. Then he carefully counted out the French fries, divided them in two piles and neatly placed one pile in front of his wife. He took a sip of the drink, his wife took a sip and then set the cup down between them.

    As the man began to eat his few bites of hamburger the crowd began to get restless. Again you could tell what they were thinking, “That poor old couple. All they can afford is one meal for the two of them.”

    As the man began to eat his French fries one young man stood and came over to the old couple's table. He politely offered to buy another meal for the old couple to eat. The old man replied that they were just fine. They were used to sharing everything.

    Then the crowd noticed that the little old lady hadn't eaten a bite. She just sat there watching her husband eat and occasionally taking turns sipping the drink.

    Again the young man came over and begged them to let him buy them something to eat. This time the lady explained that, no, they were used to sharing everything together.

    As the little old man finished eating and was wiping his face neatly with a napkin the young man could stand it no longer. Again he came over to their table and offered to buy some food.

    After being politely refused again, he finally asked a question of the little old lady. “Ma'am, why aren't you eating? You said that you share everything. What is it that you are waiting for?”

    She answered, “The teeth”.

    Changing technology stimulates (刺激) the brain and increases intelligence. But that may only be true if the technology challenges us. In a world run by intelligent machines, our lives could get a lot simpler. Would that make us less intelligent?

    After the Industrial Revolution, machines began to replace manual workers. The process played out in agriculture as well as manufacturing so that groups of agricultural workers were replaced and forced to move to cities to make a living.

    When machines took away much of the manual work, people became less physically active and gained weight. The sedentary (久坐的) lifestyle contributed to a worldwide spreading of overweight and related metabolic disorders such as heart disease, secondary diabetes and kidney disease .

    As our bodies rested, our brains were forced to work harder, however. It is much more difficult to drive through an overcrowded modern city than it is to move around in a small rural village, for instance. Modern jobs are also more complex and urgent and they require more education because employees need to process new information quickly. Even during our leisure time, our brains work harder due to greater availability of books and explosion of audiovisual media, for entertainment, study, music, news, and so forth.

    Now in the Internet age, the amount of information grows fast along with the advance of electronic technologies. The number of people with whom we interact electronically grows by leaps and bounds thanks to the ease of use of social media like Facebook and Twitter.

    All of this extra work for our brains makes us more intelligent. That helps explain why human intelligence increases steadily from generation to generation in all developed countries, a phenomenon named the Flynn Effect. Of course, there are other reasons, including improved nutrition, better medical practices that reduce brain damage, and improved sanitation and public health that reduce diseases of childhood.

    In the P.G Wodehouse novels, Bertie Wooster got away with being a fool because Jeeves was there to back him up with superior brain power. Similarly, people of the future are at risk of being less intelligent because machines will do their thinking for them.

    Artificial intelligence is taking over many human jobs. For instance, planes are being flown much of the time by automatic pilots. Moreover, the complex problem of controlling air traffic around large modern airports is also achieved by artificial intelligence that operates well beyond the capability of mere human air traffic controllers.

    Artificial intelligence exists in many fields of modern life for the simple reason that intelligent machines can already outperform humans, including some aptitudes (天资) which were once thought to be a human advantage, such as playing chess or recalling details in a game of Jeopardy.

    Machine intelligence is increasing much faster than human intelligence. As machines get smarter, they will do more of our thinking for us and make life easier.

    Instead of struggling to identify ourselves to some electronic system via passwords that are secure only if they are hard to remember, the system will work harder to identify us using biometrics (生物测定学) such as fingerprints or even the individual sound of our hearts. More technologies of the future may also be voice-activated so that we will talk with machines much as we would talk to a friend.

    In the future, the electronic assistant will develop to the point where it serves similar functions as a real living chief male servant of a house, fulfilling requests such as: “Organize a dinner party for six on Thursday, Jeeves, and invite the usual guests .”

    At that point, our long struggle with challenging technologies is at an end. Like Bertie Wooster, we can take it easy knowing that the hard work of planning and organizing is being done by a better brain—the electronic assistant. Starved of mental effort, our brains will return to an earlier or less advanced form.

    The future is still in the fog.

    Do you know the difference between a food chain anda food web? Food chains show how a living thing such as a plant or an animal gets its energy. A food web consists of multiple food chains and includes many more plants and animals than a food chain includes. This diagram shows a food chain within a food web of the African savanna.

    Before the 1830s, most newspapers were sold through annual subscriptions in America, usually $8 to $10 a year. Today $8 or $10 seems a small amount of money, but at that time these amounts were forbidding to most citizens. Accordingly, newspapers were read almost only by rich people in politics or the trades. In addition, most newspapers had little in them that would appeal to a mass audience. They were dull and visually forbidding. But the revolution that was taking place in the 1830s would change all that.

    The trend, then, was toward the "penny paper" ­a term referring to papers made widely available to the public. It meant any inexpensive newspaper; perhaps more importantly it meant newspapers that could be bought in single copies on the street.

    This development did not take place overnight. It had been possible(but not easy)to buy single copies of newspapers before 1830, but this usually meant the reader had to go down to the printer's office to purchase a copy. Street sales were almost unknown. However, within a few years, street sales of newspapers would be commonplace in eastern cities. At first the price of single copies was seldom a penny­usually two or three cents was charged­and some of the older well­known papers charged five or six cents. But the phrase "penny paper" caught the public's fancy, and soon there would be papers that did indeed sell for only a penny.

    This new trend of newspapers for "the man on the street" did not begin well. Some of the early ventures(企业)were immediate failures. Publishers already in business, people who were owners of successful papers, had little desire to change the tradition. It took a few youthful and daring businessmen to get the ball rolling.