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.

    If you watch British television on Friday March 15,you might be surprised to see celebrities wearing funny red noses and joking around. But don't worry. They're not mad. It's all part of a biannual fund-raising event called Red Nose Day.

    Organized by the charity Comic Relief, founded in 1985 by two British comedians, the aim of the event it is to raise money to fight poverty and injustice in the UK and Africa. Celebrities and public figures support the event by making appearances on comic TV shows broadcast by the BBC. This year, for example, UK Prime Minister David Cameron appeared in a music video by One Direction, which the band produced for the event.

    But Britons don't just raise money for charitable causes on one day a year. They do it all year round. One way of doing so is-by shopping in charity shops. These small, inconspicuous shops sell clothes, books and household goods just like any other shop But there's one big difference—everthing sold in the shops is second-hand.

    There are nearly 10,000 charity shops in the UK, according to the Charity Retail Association. Their business model is simple: Anybody who has things they don't want anymore can donate them to a charity shop, where they are checked for damage, cleaned and priced. Most items go back on sale at a small part of their original price and the money that is made by selling them is used for a charitable cause.

    The idea of buying used clothes may sound off-putting, but for shoppers who have less spending money, such as the elderly or those in low-paying jobs, it has been a welcome option for years. Now, shopping at charity shops is also becoming popular with young people looking for alternative fashion." You can find very unique clothes for a very cheap price. It doesn't bother me that other people may have worn them. I simply wash them before I wear them," said Anne Marie, a 19-year-old Internet user from the US, in a comment on a Yahoo forum.

    So next time you spot a charity shop, why not go inside? Who knows, you might find a lovely dress for just a few pounds. Even better, you can enjoy wearing it in the knowledge that your money helped a good cause.

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    Inside the pleasingly fragrant café, So All May Eat(SAME) in downtown Denver, the spirit of generosity is instantly noticeable: A donation box stands in place of a cash register. Customers here pay only what they can afford, no questions asked.

    A risky business plan, perhaps, but SAME Café has done one unchangeable thing in the Mile High City for six years: Open only at midday, the restaurant provides poor local people with healthy, delicious lunches six days a week. Those unable to pay for their meals can instead volunteer as waiters and waitresses, and dishwashers, or look after the buildings and equipment for the cafe.

     “It's based on trust, and it's working all right” , says co-owner Brad Birky , who started the café in 2006. With his wife Libby. Previously volunteering at soup kitchens, the Birkys were dissatisfied with the often unhealthy meals they served there.

     “We wanted to offer quality food in a restaurant where everyone felt comfortable ,regardless of their circumstances,” Birky says. SAME's special lunch menu changes daily and most food materials are natural and grown by local farmers.

    The café now averages 65 to 70 customers (and eight volunteers) a day. And the spirit of generosity behind the project appears to be spreading. In early 2007,one volunteer who had cleared snow for his meals during the long winter said goodbye to the Birkys,” He said he was going to New Orleans to help with the hurricane cleanup,” says Birky.

    Australia is a big country, but it is easy to get around. The untouched beaches that go for miles and deserts that touch the horizon(地平线) are just there, waiting to be reached and explored. You can explore the big country in different ways.

Air

    Flying is the best way to cover large distances in a short time. You can spend more time on the Australia's landscapes(陆地风光) and relaxing lifestyle. Moreover, competition among airlines makes great flying fees available for you.

Drive

    Australia has a big network of well-kept roads and some of the most beautiful touring routes in the world. You have no trouble finding car rental companies at major airports, central city and suburbs(怒火).

Bus

    Bus travel in Australia is comfortable, easy and cheap. Buses generally have air conditioning, reading lights, adjustable(可凋) seats and videos. Services are good for everyone, frequent.

Rail

    Train travel is the cheapest and gives you an insight into Australia's size, all from the comfort of your carriage. Scheduled services are a great way to get quickly between our cities and regional centers.

Ferry(轮渡)

    The Spirit of Tasmania runs a passenger and vehicle ferry service between Melbourne and Tasmania nightly. Extra services are running during summer rush hours. Sea-link ferries connect South Australia and Kangaroo Island several times a day. Ferries connect suburbs in our capital cities.

    Besides all of above, you can also experience some of the longest tracks and trails in the world in central Australia-impressive journeys of a thousand kilometers or more that can take several weeks to complete.

    When the natural climate changes due to global warming, it can surely affect seals. The majority of them live in the Antarctic region so as the ice is melting, their natural habitat（栖息地）can be seriously affected. These changes don't take place overnight. They can be the result of many years of additional temperatures in the area. The seals then have to find ways to adapt.

    Seals depend on the cool air currents to bring plenty of food for them. When the temperatures get higher, there is less and less food and the seal population starts to get depleted. Mothers aren't healthy enough to feed their babies. Many of them end up abandoned as the mothers have to leave to find their own source of food.

    The fact that their desire to produce young can be changed by the warmer temperatures is frightening too. It is also believed that the warmer temperatures can allow different diseases and viruses to attack the seals. This is a huge concern as they can rapidly wipe out huge numbers of seals out there.

    However, these changes in climate and temperature aren't all bad for other species of seals. Scientists have found that those living in warmer climates are producing more young due to the changes. Research also shows that the females are moving further to find food and water. When they are out of the reach of the governing males, they are more willing to accept the moves of other males in the group.

    This is good news too because it means that there will be more selection in the gene pool（基因库）for future generations. It can help the seals as a species adapt to changes in their natural environment more easily.

    The climate change problem for seals is directly linked to humans. When we take action to change what we let out into the environment, we will make positive changes for the seals. However, it is going to take a very long time to reverse（彻底改变）the effects of what has already been done.

    We have a strange obsession with the concept of perfection. “If I have the perfect parents and perfect grades, then I would be happy.” Under cultural influence, we seek what we can't have without remembering that we don't actually need to be perfect. Imperfection allows us to be human.

    Parents, teachers and other high-achieving peers will have us believe that we must be perfect if we wish to remain competitive. However, what job or school requires you to have a 2400 SAT, 4.0 GPA and develop a cure for some form of cancer by the age of 18? Although these would be great achievements, are they worth the cost of sleep? We feel like we need the perfect grades to get into the perfect college that will provide us with the perfect education necessary to obtain the perfect job. With this misconception, when writing our resumes(简历), we then seek out experiences that we think may help build a good name for ourselves. Feeding on our thirst for perfection, some college and career industries have been set up claiming to help us reach our goals.

    The truth is, you only need to be good enough. Don't worry about anything secondary to your passions. You won't become an expert at anything if you spend your time trying to succeed in everything you do. You only become an expert when you devote your time to the one or two projects that truly bring you joy.

    As members of this society, we have a responsibility to be excellent in what we do, not perfect. Although perfection can be a goal, it should not be the only goal. We only have 24 hours in a day. Thus, we need to prioritize(优先选择)what we want to do and cut out the activities we cannot do. If you enjoy debating, take a law class and see how it suits you. If you enjoy cooking, experiment in the kitchen and see what you can make!

    Try as hard as you can and let your future worry about itself. Worry about your task at hand and you will be successful in achieving your dreams. Above all, remember that you are going to be okay.