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.

    The Renaissance，considered by modern scholars to have been the time between 1,300 and 1,600，was a period of European history when many new inventions and beliefs came into being.

    The Renaissance is traced back to rich Italian cities such as Florence，Milan，and Venice.In these cities businessmen started to spend their extra money on things like painting and education，and to consider new techniques of banking and systems of government.A new type of scholar，the humanist(人文主义者)arose.Humanism was concerned with humankind and culture.Latin and Greek，literature and philosophy，music and mathematics were among the subjects humanists studied.

    The Renaissance gave rise to new forms of painting and  sculpture.During  the  Renaissance，artists were no longer regarded as mere artisans(工匠)．Many artists drew on mathematics in order to become more accurate in their measurements(度量)and to make sure an object was presented in realistic proportions.They also studied the way light hits objects and the ways our eyes perceive it.A new kind of paint，called oil paint，was invented.

    The Renaissance affected all of the society.Many people became interested in politics，and the world outside their towns.They became explorers，businessmen，etc.The effect on religion was especially strong.In the Middle Ages people were primarily concerned with serving the church and getting to heaven.But the increase in arts  and education gave  people things to look forward to in life，and made them lose interest in the church.

    The  Renaissance  produced  many  great minds.Leonardo da Vinci was one of the greatest，although he was not regarded that way at the time.Among his many works of art were Mona Lisa and The Last Supper.He is also regarded as a great inventor，and is credited for coming up with the idea of the helicopter.

    Early birds-people who feel most energetic in the morning-tend to make healthier food choices throughout the day than night owls(夜猫子) , according to a new study.

    "Evening types had more irregular meal times," notes study author Mirkka Maukonen, studying human nutrition and obesity(肥胖) in Finland.

    Her study focused on people's risk of heart disease and their eating habits. Participants described when and what they had eaten during the past two days.

Maukonen's team then looked at l,854 people's lifestyle. After analyzing the data, the researchers found that both morning and evening people consumed approximately the same number of calories over a whole day.  However, night owls tended to eat their meals later than early birds. Before 10:00 am, night owls consumed less food than early birds. More of their calories came from sugar. After 8:00 pm, the night owls ate more sugar and fat. Meanwhile ,early birds ate more protein during both the morning and the evening hours.

    "Night owls tend to be less healthy than early risers," notes Courtney Peterson who studies diet and meal timing. "They are more likely to get heart disease or cancer. The fact that night owls tend to eat more junk food probably plays a role," Peterson says. "Other factors(因素) also can ruin a night owl's health. Night owls generally sleep worse," says Peterson. "Poor sleep has been linked to unhealthy food choices. "

    Peterson and Maukonen say night owls tend to have poor eating habits. But that doesn't necessarily mean that being a night owl makes a person a poor eater. It could be the reverse- eating poorly could affect people's sleep habits.

"The new findings should serve as a wake-up call to night owls. For them, the new results should encourage paying attention to healthier lifestyle choices," says Maukonen. 28. How did Maukonen do research about people's risk of heart disease?

    The burst of barking suddenly woke me up. It was 2:30 a.m. in the early morning. Wondering why Rock was making so loud noises, I decided to go to him. By the time I made it to the bottom of the stairs, he was running up. I felt strange, for he had never come up the stairs, no matter what. I think that was his way of telling me, “We've got to go back up.”

    When I got to the top of the stairs, I turned around and saw a light on, but I didn't remember leaving one on. I walked downstairs again, and that's when I saw fire. I immediately shouted to my wife to wake up and get our three kids. I grabbed a knife and cut out the plastic that covered the window to the porch roof. I then forced open the window and kicked out the screen. I got everybody out on the roof and threw a blanket out there so we wouldn't slip off. It was cold, January cold. Then I started screaming for help. But help never came.

    I was scared of heights, but I couldn't let my family burn up. So I just jumped off the roof and got the wind knocked out of me when I landed.

    I found our ladder, placed it against the house, and climbed back up to the roof. I wrapped my arms around my daughter and carried my nine-month-old with my teeth, by his little sleeper. Then I climbed down the ladder. Once on the ground, I had my little girl hold her brother, and I went back up to the roof to get my other daughter. Then I went back up again and got my wife. I tried to get my dog, but he just disappeared in the black smoke. I never saw Rock alive again.

    Many people believe that you lose the ability to learn new languages as you get older. Language experts, however, will tell you that you're never too old to learn a new language. As you get older, it can be more difficult to learn a new language, though.

    Children and adults learn new languages in different ways. For children, language is their life. They study for thousands of hours every year, because they need to learn languages to become part of their communities. Adults, on the other hand, are already part of a language community. Learning a new language means becoming part of another language community, and adults rarely get the chance to practice as much as young children do.

    Moreover, children learning a new language are expected to make mistakes. This gives them freedom when learning to be daring and confident. Adults, however, often feel stressed to be perfect when learning a new language. This can discourage many people and make it even harder to learn a new language.

    When young children learn a new language, they come to see various languages as a “normal” part of society. This mindset helps them to learn a new language without feeling like they're doing something unusual or “too hard”.

    So if you want to learn a new language, go for it! It's never too late to learn a new language. If you're older, it may take more work, but it can be done. If you're a young child, though, now is the time to step out and learn a new language!

I am asked repeatedly why anyone would want to keep an "'ugly" building or a building that is dirty and clearly in need of work, I guess you could say we preservationists (文物保护者)look at buildings through a different angle - an angle that can see the swan in the ugly duck the story in the simple lines, and the book behind the cover.

The Queen Emma Building is remembered by many as one of the ugliest buildings in town. Yet the angle from which a preservationist views the building is that it is uniquely constructed with an artistical sun shield to block the sunlight, a decorative wall designers used concrete bricks to form. Unfortunately, it was removed in 20il, making the building one of many contemporary buildings in town.

Other times, when a beautiful site is replaced by a "horrible" building, people hate it and can't get over their anger, even when that: "horrible" building becomes an important part of our story. This is particularly true in San Francisco with many Victorian buildings, which are many preservationists' favorite. Yes, it was a tragedy, that many Victorian buildings got torn down several decades ago, but those losses also tell another important story. It tells the story of the1950s and 1960s when there was hope for a more equal society with in expensive housing for the working class. Should that history be wiped from our memories? 

Preservation is not just about keeping pretty, well-kept buildings, but about holding on to parts of our history - not just the history of huge events, but the story of how everyone used to go to a certain corner market. Our history cannot be told only in buildings that meet someone's criteria of beauty, sometimes our history is, painful, but no less important.