By now, we are all aware that social media has had a powerful influence on our culture, in business, on the world at large. Social media websites revolutionized the way people communicate and socialize on the Web. However, besides seeing your friends' new baby on Facebook, or reading about Justin Bieber's latest conflict with the law on Twitter, what are some of the real influences?

    Social networks offer the opportunity for people to reconnect with their old friends and acquaintances, make new friends, share ideas and pictures, and many other activities. Users can keep pace with the latest global and local developments, and take part in campaigns and activities of their choice. Professionals use social media sites like Linkedln to improve their career and business development. Students can work together with their peers to improve their academic and communication skills.

    Unfortunately, there are a few downsides too to social networking. If you are not careful, immoral people can target you for cyber bullying(网络欺凌) and disturbance on social sites. School children, young girls, and women can fall victim to online attacks which can create tension and suffering. If you are a victim of cyber bullying, do not take it lying down, but try to take appropriate legal action against the attacker.

    Many companies have blocked social networks as addicted employees can distract (分心)themselves on such sites, instead of focusing on work. In fact, studies show that British companies have lost billions of dollars per year in productivity because of social media addiction among employees.

    Also, what you carelessly post on the Net can come back to trouble you. Leaking personal information on social sites can make users easily harmed to crimes like identity theft, stalking(尾随犯罪), etc. Many companies perform a background check on the Web before hiring an employee.  If a potential employee has posted something embarrassing on social media, it can greatly affect their chances of getting the job. The same holds true for our relationships too, as our loved ones and friends may get to know if we post something undesirable on social networks.

    Social media has its advantages and drawbacks as each coin has two sides. It is up to each user to use social sites wisely to improve their professional and social life, and exercise caution to ensure they do not fall victim to online dangers.

    The bus was full of the sounds of laughing and yelling fifth graders. They were on their way to the zoo for a class trip. Mario was excited to see the zoo, but there was one problem. It was ten o'clock in the morning, but his stomach was already grumbling(咕咕叫). He reached down and grabbed his lunch bag. Opening it, he saw that it contained a peanut butter and jelly sandwich, an orange, and two cookies. Mario sighed. He always had peanut butter and jell.

    “Trade you lunches,” he said to the boy seated next to him on the bus．

    “Okay,” said Mark as he handed his brown bag to Mario．

    Mario opened it and was hit with the smell of tuna(金枪鱼). Mario wrinkled his nose and quickly closed the bag. He leaned forward and tapped the shoulder of the girl in front of him.” Swap lunches, Toni?” he asked．

    “Hmm, okay,” said Toni．

    Mario smiled. This was fun. But when he looked into the bag, he frowned. What a disappointment! A ham sandwich, but no cookies! He had to have cookies．

    Mario turned in his seat. “Want to trade lunches?” he asked Juana．

    “Definitely!” said Juana. She grabbed his lunch and tossed hers onto his lap．

    He opened the lunch bag. Pizza! He reached into the bag to grab it. Oh, no! The pizza was hard. He could hit a home run with pizza that hard.

    Mario twisted in his seat. One last try, he told himself. “Hey, Mona! Trade lunches?”

    Three rows behind him, Mona seemed hesitant: Finally, she nodded. She passed her lunch forward, and he passed his back．

    Mario took a deep breath and opened the bag. It was a peanut butter and jelly sandwich, an orange, and two cookies. The sandwich was a little squashed(挤压), and one of the cookies was broken.

    Mario ate it anyway. And it was delicious.

    A unique experience awaits you at the Centre for Alternative Technology on the edge of the beautiful Snowdonia National Park.

    Over thirty years ago a group of people decided to try out alternative technologies. They chose a remote empty place, where rock used to be dug from the ground, as their base. Here experiments offering solutions to the world's energy problems were carried out, and nowadays many of these ideas have become common practice. You can experience all these for yourself in just one day with us, and then take away what you have learned and put it into practice at home. Be assured it will help you save on your household energy costs!

    Your visit to us begins with a ride up a steep 60-metre hillside on a railway which is worked by using the weight of water. At the top of the mountain you will enjoy beautiful views to the distant coastline. Then interactive displays show the power of wind, water and sun, while showing you what can be done in an ordinary household to reduce your influence on the planet.

    There was no soil when the project was started, so we created our organic gardens using our own home-made soil. You can enjoy woodland walks or even notice spring flowers growing on the roofs of environmentally-friendly buildings.

    In 2006 we opened our new eco-adventure playground for children, and we also run workshops where they can make models and become inventors of the future by putting wind, water or solar power into their own designs.

    The Centre for Alternative Technology is open all year round and has good rail, road and cycle links. In fact we offer a 50% reduction on the admission price if you arrive by bicycle. There is wheelchair access for disabled visitors—telephone us in advance if you would like assistance.

    Wolves are important animals in the traditions and stories of most Native American tribes. To Native Americans, wolves often represent bravery. The animals also are signs of strength, loyalty, and success at hunting. Other cultures--such as the ancient Celtic and Nordic peoples-also placed high value on wolves.

    However, from the wolves in horror films to the wolves in children's stories, wolves get a bum rap(不公正的惩罚) in both literature and English expressions.

    To begin with, there is the term lone wolf. The lone wolf isn't a bad person. But they like to do things on their own. However, the term can mean something less than desirable. Lone wolf makes you think the person doesn't want to be around people because he or she dislikes them.

    Now, let's move on to the home.

    Parents might criticize their children for wolfing down their food. In other words, the child eats very quickly and without care. And if someone says a child was raised by wolves, that child has bad manners and is behaving like a wild animal. A wolf at the door means someone to whom you owe money is waiting just outside your door.

By the way, there are two popular wolf-related expressions that come from Aesop, the ancient Greek storyteller.

    The first is a wolf in sheep's clothing. A wolf in sheep's clothing describes someone who acts and looks nice on the outside but is bad on the inside.

    Aesop's other wolf fable also involves a shepherd, but not a hardworking one. He is known as the boy who cried wolf. People who cry wolf are not trusted. People are so familiar with this story, you simply have to say cry wolf for them to know what you mean.

    Dr. Nancy Roman, born in 1925, who was celebrated as a pioneer for female scientists and had advanced the launch of the Hubble Space Telescope, died on Dec 25, 2018.

    When Nancy Roman asked for permission to take a second algebra (代数)course in high school,a teacher demanded to know "what lady would take mathematics instead of Latin". In college, a professor admitted that he often tried to prevent women from majoring in physics but Nancy stuck to it. And after receiving Doctor's degree in astronomy. , she found a professional home at NASA(美国宇航局)In 1959, Dr. Roman became the first chief of astronomy at NASA. headquarters, a role that made her one of the agency's first female leaders.

    Dr Roman spent much of her career helping develop, fund and promote technology that would help scientists see more clearly beyond Earths atmosphere. But her most well-known work was perhaps leading to design the Hubble Space Telescope the first major telescope to be sent into space for the purpose of gathering photographs and data from the universe. She was, therefore, named as "the mother of Hubble".

    "She made it possible to get the early telescope up into space to learn what needed to be learned," said science historian Bob Zimmerman: and her hard-nosed nature helped get the telescope built.

    The telescope did not launch until 1990, a little more than a decade after Dr Roman retired, but when it did, its photographs of the universe thrilled the world.  I am glad, "she once told Science, "I ignored the people who told me that I could not be an astronomer. "

    Like infectious diseases, ideas in the academic world are epidemic (传染的). But why some travel far and wide while equally good ones has been a mystery? Now a team of computer scientists has used an epidemiological model to simulate (模仿) how ideas move from one academic institution to another. The model showed that ideas originating at famous institutions caused bigger "epidemics" than equally good ideas from less famous places, explains Allison Morgan, a computer scientist at the University of Colorado Boulder.

    "This implies that where an idea is born shapes how far it spreads," says senior author Aaron Clauset.

    Not only is this unfair— "it reveals a big weakness in how we're doing science," says Simon DeDeo, a professor of social and decision sciences at Carnegie Mellon university, who was not involved in the study. "There are many highly trained people with good ideas who do not end up at top institutions. They are producing good ideas, and we know those ideas are getting lost," DeDeo says. "Our science, our scholarships, is not as good because of this."

    The Colorado researchers first looked at how five big ideas in computer science spread to new institutions. They found that hiring a new faculty member accounted for this movement a little more than a third of the time--and in 81 percent of those cases, transmissions took place from higher – to lower-prestige (声望) universities. Then the team simulated the spread of ideas using an infectious disease model and found that the size of an idea "epidemic" depended on the prestige of the originating institution.

    The researchers' model suggests that there "may be a number of quite good ideas that originate in the middle of the pack, in terms of universities." Clauset says. There is a lot of good work coming out of less famous places, he says: "You can learn a huge amount from it, and you can learn things that other people don't know because they're not even paying attention."