No one is sure how the ancient Egyptians built the pyramids near Cairo. But a new study suggests they used a little rock‘n'roll. Long-ago builders could have attached wooden pole s to the stones and rolled then across the sand, the scientists say.
“Technically, I think what they're proposing is possible,” physicist Daniel Bonn said.
People have long puzzled over how the Egyptians moved such huge rocks. And there's no obvious answer. On average, each of the two million big stones weighed about as much as a large pickup truck. The Egyptians somehow moved the stone blocks to the pyramid site from about one kilometer away.
The most popular view is that Egyptian workers slid the blocks along smooth paths. Many scientists suspect workers first would have put the blocks on sleds(滑板). Then they would have dragged them along paths. To make the work easier, workers may have lubricated the paths either with wet clay or with the fat from cattle. Bonn has now tested this idea by building small sleds and dragging heavy objects over sand.
Evidence from the sand supports this idea. Researchers found small amounts of fat, as well as a large amount of stone and the remains of paths.

However, physicist Joseph West thinks there might have been a simpler way , who led the new study . West said , “I was inspired while watching a television program showing how sleds might have helped with pyramid construction . I thought , ‘Why don't they just try rolling the things?'“A square could be turned into a rough sort of wheel by attaching wooden poles to its sides , he realized . That , he notes , should make a block of stone” a lot easier to roll than a square”.
So he tried it.
He and his students tied some poles to each of four sides of a 30-kilogram stone block. That action turned the block into somewhat a wheel. Then they placed the block on the ground.
They wrapped one end of a rope around the block and pulled. The researchers found they could easily roll the block along different kinds of paths. They calculated that rolling the block required about as much force as moving it along a slippery(滑的)path.
West hasn't tested his idea on larger blocks, but he thinks rolling has clear advantages over sliding. At least, workers wouldn't have needed to carry cattle fat or water to smooth the paths.

    How could we possibly think that keeping animals in cages in unnatural environments, mostly for entertainment purposes, is fair and respectful?

    Zoo officials say they are concerned about animals. However, most zoos remain “collections” of interesting “things” rather than protective habitats. Zoos teach people that it is acceptable to keep animals bored, lonely, and far from their natural homes.

    Zoos claim to educate people and save endangered species, but visitors leave zoos without having learned anything meaningful about the animals' natural behavior, intelligence, or beauty. Zoos keep animals in small spaces or cages, and most signs only mention the species' name, diet, and natural range. The animals' normal behavior is seldom noticed because zoos don't usually take care of the animals' natural needs.

    The animals are kept together in small spaces, with no privacy and little opportunity for mental and physical exercise. This results in unusually and self-destructive behavior called zoo-chosis(圈禁性精神病). A worldwide study of zoos found that zoochosis is common among animals kept in small spaces or cages. Another study showed that elephants spend 22 percent of their time making repeated head movements or biting cage bars, and bears spend 30 percent of their time walking back and forth, a sign of unhappiness and pain.

    Furthermore, most animals in zoos are not endangered. Captive breeding(圈养繁殖) of endangered big cats, Asian elephants, and other species has not resulted in their being sent back to the wild. Zoos talk a lot about their captive breeding programs because they do not want people to worry about a species dying out. In fact, baby animals also attract a lot of paying customers. Haven't we seen enough competitions to name baby animals?

    Actually, we will save endangered species only if we save their habitats and put an end to the reasons people kill them. Instead of supporting zoos, we should support groups that work to protect animals' natural habitats.

    People often ask which is the most difficult language to learn, and it is not easy to answer because there are many factors to take into consideration. Firstly, in a first language the differences are unimportant as people learn their mother tongue naturally, so the question of how hard a language is to learn is only relevant when learning a second language.

    A native speaker of Spanish, for example, will find Portuguese much easier to learn than a native speaker of Chinese, for example, because Portuguese is very similar to Spanish, while Chinese is very different, so first language can affect learning a second language. The greater the differences between the second language and our first, the harder it will be for most people to learn.

    Many people answer that Chinese is the hardest language to learn, possibly influenced by the thought of learning the Chinese writing system, and the pronunciation of Chinese does appear to be very difficult for many foreign learners. However, for Japanese speakers, who already use Chinese characters in their own language, learning writing will be less difficult than for speakers of languages using the Roman alphabet.

    Different cultures and individuals will find different languages more difficult. In the case of Hungarian for British learners, it is not a question of the writing system, which uses a similar alphabet, but the grammatical complexity, though native speakers may find it easier, struggling with languages that the British find relatively hard.

    No language is easy to learn well, though languages which are related to our first language are easier. Learning a completely different writing system is a huge challenge, but that does not necessarily make a language more difficult than another. In the end, it is impossible to say that one language that is the most difficult language in the world.

    All over the world people enjoy sports. Sports help to keep people healthy, happy and help them to live longer.

    Sports change with the season. People play different games in winter and summer.

    Games and sports often grow out of people's work and everyday activities. The Arabs use horses or camels in much of their everyday life; they use them in their sports, too.

    Some sports are so interesting that people everywhere go in for them. Football, for example, has spread around the world. Swimming is popular in all countries near the sea or in those with many rivers.

    Some sports or games go back to thousands of years, like running or jumping. Chinese boxing, for example, has a very long history. But basketball and volleyball are rather new. Neither one is a hundred years old yet. People are inventing new sports or games all the time.

    People from different countries may not be able to understand each other, but after a game they often become good friends. Sports help to train a person's character(性格). One learns to fight hard but fight fair, to win without pride and to lose with grace(体面).

    A large body of research has been developed in recent years to explain many aspects of willpower. Most of the researchers exploring self-control do so with an obvious goal in mind: How can willpower be strengthened? If willpower is truly a limited resource, as the research suggests, what can be done to make it stay strong?

    Avoiding temptation (诱惑) is an effective method for maintaining self-control, which is called the "out of sight, out of mind" principle. One recent study, for instance, found office workers less attracted to candy in the desk drawer than that on top of their desks, in plain sight.

    The research suggesting that we possess a limited reservoir of self-control raises a troubling question. When we face too many temptations, are we to fail? Not necessarily. Researchers don't believe that one's willpower is ever completely exhausted. Rather, people appear to hold some willpower in reserve, saved for future demands. The right motivation allows us to tap into those reserves, allowing us to carry on even when our self-control strength has been run down. High motivation might help overcome weakened willpower-at least to a point.

    Willpower may also be made less vulnerable (脆弱) to being exhausted in the first place.

    Researchers who study self-control often describe it as being like a muscle that gets tired with heavy use. But there is another aspect to the muscle comparison, they say. While muscles become exhausted by exercise in the short term, they are strengthened by regular exercise in the long term. Similarly, regular practices of self-control may improve willpower strength.

    The evidence from willpower-exhaustion studies also suggests that making a list of resolutions on New Year's Eve is the worst possible approach. Being exhausted in one area can reduce willpower in other areas, so it makes more sense to focus on a single goal at a time. In other words, don't try to quit smoking, adopt a healthy diet and start a new exercise plan at the same time. Taking goals one by one is a better approach. Once a good habit is in place, Baumeister says, you'll no longer need to draw on your willpower to maintain the behavior. Eventually healthy habits will become routine, and won't require making decisions at all.

    Give yourself a test. Which way is the wind blowing? How many kinds of wildflowers can be seen from your front door? If your awareness is as sharp as it could be, you'll have no trouble answering these questions.

    Most of us observed much more as children than we do as adults. A child's day is filled with fascination, newness and wonder. Curiosity gave us all a natural awareness. But distinctions that were sharp to us as children become unclear; we are numb(麻木的）to new stimulation(刺激), new ideas. Relearning the art of seeing the world around us is quite simple, although it takes practice and requires breaking some bad habits.

    The first step in awakening senses is to stop predicting what we are going to see and feel before it occurs. This blocks awareness. One chilly night when I was hiking in the Rocky Mountains with some students, I mentioned that we were going to cross a mountain stream. The students began complaining about how cold it would be. We reached the stream, and they unwillingly walked ahead. They were almost knee-deep when they realized it was a hot spring. Later they all admitted they'd felt cold water at first.

    Another block to awareness is the obsession(痴迷) many of us have with naming things. I saw bird watchers who spotted a bird, immediately looked it up in field guides, and said, a "ruby-crowned kinglet" and checked it off. They no longer paid attention to the bird and never learned what it was doing.

    The pressures of "time" and "destination" are further blocks to awareness. I encountered many hikers who were headed to a distant camp-ground with just enough time to get there before dark. It seldom occurred to them to wander a bit, to take a moment to see what's around them. I asked them what they'd seen. "Oh, a few birds," they said. They seemed bent on their destinations.

    Nature seems to unfold to people who watch and wait. Next time you take a walk, no matter where it is, take in all the sights, sounds and sensations. Wander in this frame of mind and you will open a new dimension to your life.