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.

    When men get together, they seldom talk about their feelings or inner thoughts. However, they talk about a lot, like their newest computer, how to repair their car, or even business.

    Talk might move to the best place to find fish or women, jump to computer games, then continue to the sport of the season. They also like to tell jokes each other and spend a fair amount of time playing one-up and boasting (吹牛). Men seldom call each other to chat.

    When man meets woman, he usually wants to make a good impression. Many single men try hard to carry on amusing, fun, and pleasant conversations. They use conversation to discover her interests and feelings in order to learn how to be attractive to her.

    Some men, either out of nervousness or ignorance, spend most of the time talking about themselves, often appearing to show off their achievements or talk endlessly about their problems or work. Even the quietest man talks to his woman when love is new.

    When women get together, they talk about feelings and relationships, their work and their family. They enjoy talking but also want the give and take of talk, then listen. Women often call each other to chat. Conversation is an important part of most women's lives.

    As relationships progress, however, many a man turns on the television and forgets how to talk. This raises anger and cry from his woman partner who says, “You never talk to me anymore.” Some men start talking. Many, however, mainly discuss their own achievements and problems.

    When the woman starts talking about her favorite subjects: feelings, family, relationships, friends and her work, many men lose interest or bring the conversation back to themselves. Pretty soon, the man is back to staring at the television each night, wondering where his relationship has gone. The woman is talking to her friends, mom, sister, or neighbor, often about that very relationship and how she is hurting.

    Nowadays, a new method is used to decide who are the top students in school. The best students are those who not only get high marks, but also follow the rules and the behavior standards for middle school students. Here are some of the new rules and standards.

    Tell the truth. Have you ever copied someone else's work in an exam? If you have, then don't do it again! That's not something an honest student should do. If you have played computer games for two hours in your room, don't tell your parents you were doing your homework.

    Learn to be loving and caring. Good students love animals and care about other people.

    Learn to work together with others. It would be more fun when more people work together. Did you quarrel(争吵) with your teammates when your basketball team lost? Only working together can make your team stronger. Be friendly to the people you are with. Try to think of others, instead of only yourself.

    Be open to new ideas. Have you ever thought that people could live on the moon? Perhaps you'll discover Earth II some day. Don't look down upon new ideas. Everyone's ideas are important. You should welcome them, because new ideas make life better for everyone.

    Use the Internet carefully. The Internet can be very useful for your study. Some websites on the Internet are not for kids, so make sure to visit the web pages that are good for you. You can use the web for fun or homework. Can't you find any good websites for children?

    City College

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    All high school graduates and anyone 18 years of age or older, with or without a high school diploma, are suitable for admission. Individuals under the age of 18 who possess a high school diploma are also suitable for admission.

    HOW TO ENROLL IN CREDIT COURSES

    New and readmitted students must complete and hand in a credit admissions application form available online at www.ccsf.edu.

    BEFORE YOU REGISTER:

    Learn about your skill level in English and Math through our assessment service;

    Attend an orientation (新生报到会) to hear about support services

    Meet with a counselor (adviser) to select your courses;

    Find out if you are required for attending the entrance examinations.

    HOW TO ENROLL IN NONCREDIT COURSES

    Courses in Noncredit Programs are free of charge (no enrollment fee). For information on how to enroll in noncredit courses, click here.

    PARKING

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    City College services include a bookstore, cafeteria, health center, tutoring center, career and transfer center, counseling, financial aid, library, learning resource center, student government offices, campus police, disabled students programs and more.

    British chemist David Evans has become an overnight celebrity on Chinese social media. His chemistry experiments have attracted over 2 million followers in just a few months. Evans is a chemistry professor at the Beijing University of Chemical Technology. The 60-year-old always wears a white lab coat, a pair of safety goggles (护目镜), and smiles often. Some web users say he looks just like the “grandpa of KFC”.

    Evans has posted videos of various experiments. His most popular experiments have attracted millions of hits on video-sharing apps. Excited children's cheers and shouts can be heard in his videos. “I hope my experiments can arouse people's interest in science,” he says.

    Evans has been interested in China since childhood. In the early 1970s, before the reform and opening-up, he viewed it as a “country full of mysteries”. He first visited the Chinese mainland in 1987 to attend a chemistry conference in Nanjing, Jiangsu Province. He quit his job in the United Kingdom and moved to Beijing in 1996. Many of his friends thought he was crazy. But Evans says they just saw China's challenges but not its potential.

    Since 2011, Evans has turned to the Internet to popularize science. He learned short-video apps are also popular in small cities and rural areas. And he realized this enables him to reach more students, who lack opportunities to perform fun experiments. But even a one-minute video requires a considerable amount of work. Still, he thinks it's worth it to fulfill his responsibility to popularize science.

    His experiments always fill schools' lecture halls with laughter. Some viewers call him “a Harry Potter-like magician”, but he disagrees. “A magician never tells the secrets behind his tricks, but a scientist always gives an explanation.” He sees himself as a teacher. He performs experiments to spread knowledge, inspire thinking, remove misunderstandings and show that science can create change. Evans says he looks forward to more “chemical reactions” with China.

    Nowadays everybody seems to think that they know English. Many people speak it but few speak it really well. Practice is necessary in speaking English well.

    Reading is also one of the things that will help you to speak English better. Read whenever you can and whatever you like! Read papers and Internet sites that you like in English every day. Then, you will see that the number of known words is increasing and you are able to speak with more skills. Then you will have made the foundations and a good basis of English. It is not good to stop and get stuck there.

    Going to England or an English-speaking country is a good choice, but many people cannot afford it. If you cannot go, reading and speaking with your friends will also help you to practice your English. However, I think it is very good to visit some English-speaking country to see and test your knowledge in everyday life. You will understand the everyday usage of the language in its natural environment. There your level of English is going to improve even faster. Your ability to speak English is better. Nothing can match the excitement and happiness when a native speaker tells you that your English is very good!

    Finally, in order to speak English well, you must be persistent and do it every day. It is like playing the piano. Pianists play it every day and so should you. Include English in your life and you will see where it is going. Practice, Practice! Read, write and improve your language skills and you are on your way when you will be able to speak it with more and more confidence!