The most widespread fallacy (谬论)of all is that colds ire caused by cold. They are actually caused by viruses passing on from person to person. You catch a cold by coining into contact, directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them forever. But they do not. And in the isolated Arctic Regions explorers have reported being free from colds until coming into contact again with infected people from the outside world by way of packages and mail dropped from airplanes.

    During the First World War soldiers who spent long periods in the trenches(战壕), cold and wet, showed no increased tendency to catch colds.

    In the Second World War prisoners at the Auschwitz concentration camp，naked and starving, were astonished to find that they seldom had colds. At the Common Cold Research Unit in England, volunteers took part in experiments in which they gave themselves to the discomforts of being cold and wet for long stretches of time. After taking hot baths, they put on bathing suits, allowed themselves to be with cold water, and then stood about dripping wet in drafty rooms. Some wore wet socks all day while others exercised in the rain until close to exhaustion. Not one of the volunteers came down with a cold unless a cold virus was actually dropped in his nose.

    If then, cold and wet have nothing to do with catching colds, why are they more frequent in the winter. Despite the most pains-taking research, no one has yet found the answer. One explanation offered by scientists is that people tend to stay together indoors more in cold weather than at other times, and this makes it easier for cold viruses to be passed on.

    Hetty Robinson learnt all about money when very young. As a child, she read the financial pages of the newspaper to her rich father. Her father died when Hetty was 30, and she inherited $1 million. When she herself died in 1916, she left almost $100 million to her two children.

    Hetty made her money on the New York stock(股票) exchange. She was a financial genius. She made money so easily that people called her the Witch of Wall Street. But although she was one of the richest women in the world, she counted every cent and spent as little as possible. She didn't own a house, because she didn't want to pay taxes. So she and her children lived in cheap hotels. She spent almost nothing on clothes, and always wore the same long black dress. She washed it herself, but to save soap she only washed the bottom of the dress, where it touched the ground. Other people had their own offices, but Hetty used a desk in the bank where she kept her money, because it didn't cost anything. She sat in the bank and ate her sandwiches while she bought and sold stocks and shares. If the bank complained, she just moved all her money to another bank.

    Hetty's family paid the price for her meanness. When she was 33 she married a millionaire, Edward Green, and they had two children. But Green lost all his money, so she left him. When her son, Ned, injured his knee, Hetty didn't want to pay for a doctor, so she took him to a free hospital for poor people. Unfortunately the doctor knew Hetty was rich and he asked for money. Hetty refused and took the boy away. His leg got worse and two years later doctors removed it.

    But eventually Ned got his revenge(报复). At the age of 81, Hetty had an argument with a shop assistant about the price of a bottle of milk. She became so angry that she had a heart attack and died. So Hetty's meanness finally killed her. Ned inherited half his mother's fortune, and he spent it all on parties, holidays and expensive jewellery.

    Researchers at Brigham found about one in five teenagers now have some degree of hearing damage. The researchers did not say why hearing loss has risen, but other experts have strong suspicions. One likely culprit, they say, is MP3 players.

    An MP3 player can be dangerous to hearing when its decibel level is turned up too high. High-decibel sounds can damage nerve endings, called hair cells. If a sound is loud enough, the damage can be permanent. A loud sound can shake the membrane (薄膜) on which the hair cells sit- “like an earthquake”. That shake can break or even uproot hair cells. When that happens, the hair cells are finished. Human ears cannot regrow hair cells. Therefore, when listening to an MP3 player, set a volume limit and avoid exposure to loud sounds.

    On the other hand, the loudness of today's music may not be totally under your control. Music companies have been purposely turning up the volume. It's a trend called the fight for loudness.

    Play a CD from the 1990s. Then play a newly released tune. Don't touch the volume control. You'll probably notice that the new CD sounds louder than the old one. Why? Sound engineers who create CDs are using dynamic range compression (压缩), a technology that makes the quiet parts of a song louder and the loud parts quieter. The overall effect of compression is a louder recording.

    Many musicians and sound engineers aren't pleased. They say that compression is driving down the quality of today, s music, making it sound flat and blaring. Gray Hobish, a sound engineer, explains that music should be a combination of loudness and softness. But music companies want to make music louder so it will stand out. That's important in the competition among recording companies.

    What about listeners? Many teenagers listen to music on the go in noisy places and through headphones, all of which reduce sound quality. So young listeners may not notice the poorer quality of modem recordings. “To their ears,” says Hobish, “the music sounds fine. And they are not aware of the hidden threat of the music they are enjoying.”

    Based on new analysis, we are rapidly approaching major climate change and the effects on society and the environment could be quite severe. Geographers predict that within the next eighty years, current world climate zones could shift and some could completely disappear. Polar regions will get colder while tropical regions will get even hotter, forcing animals to migrate  (迁徙) north.

    Climate changes like these could lead to the spread of diseases. Tropical storms and hurricanes will not only increase but may also become more intense. If the changes come too quickly, animal and plant species may not be able to adapt fast enough and could disappear.

    According to Science Daily, a new study predicts that by the year 2100, many of today's familiar climates will be replaced by climates unknown in today's world. It is urgent that we reduce the risks of these far-reaching consequences for the whole world. The planet itself has been showing signs of change. In 2004, a serious tsunami created by a major earthquake killed thousands in Sumatra and in 2008, thousands died in China because of another severe earthquake. Egypt was hit in 2009 with a major earthquake and Haiti was devastated in 2010 by yet another massive earthquake.

    Within just the last few months, new reports from around the world have been coming in and most agree that our climate situation is much worse than previously thought. At this point, it doesn't matter what is causing it, but rather, what can be done about it. What's more, our world is getting more and more unstable every year. There is war and threat of war everywhere. Natural disasters are becoming more frequent and serious.

    However, other planets are experiencing global warming as well as our own and some scientists believe there may be some connection between this. No one knows anything for sure at this point because there is simply not enough data.

    With all the traditional media channels, including newspapers, magazines and television shows, shrinking, advertisers are worrying about how they can reach customers. Banners(横幅) ads on our devices are ugly and disturbing. To overcome various digital problems, the ad industry has been serving up a sneaky(不光明正大的) solution: make ads look less like ads and more like the articles, videos and posts around them.

    This trend, called native advertising, has taken over the Internet; even the websites such as NYTimes.com and Wall-Street.com are using it. On Facebook and Twitter, every 10th item or so is an ad; only the small subtitle “Sponsored（赞助）” appearing in light gray type tells you which posts are ads.

    Won't dressing up ads to make them look like reported articles mislead people? Sometimes, yes. An Interactive Advertising Bureau study found that only 41 percent of general news readers could tell such ads apart from real news stories. And it's getting worse. Advertisers worry that the “Sponsored” label discourages readers from clicking, so some websites are making the labels smaller and less noticeable. Sometimes the labels disappear entirely.

    At a recent talk about the difficulty of advertising in the new, small-screen world, I heard an ad manager tell an impressive story. She had gotten a musical performance – paid for by her soft drink client- perfectly inserted（插入）into a TV awards show, without any moment of blackness before or after. “It looked just like part of the real broadcast!” she recounted happily.

    Look, it is great that native advertising works. But if advertisers truly believe in their material, they should have no problem labeling it as advertising.

    For now native ads continue to be a fashion- with no laws governing them and no labeling standard. But that could change; the Federal Trade Commission has begun considering regulation. If the new generation of digital advertisers clean up their act according to the regulation, native ads might become more acceptable.

    A few weeks ago, I called an Uber to take me to the Boston airport for a flight home for the holidays. As I slid into the back seat of the car, the warm intonations(语调) of the driver's accent washed over me in a familiar way.

    I learned that he was a recent West African immigrant with a few young children, working hard to provide for his family. I could relate: I am the daughter of two Ethiopian immigrants who made their share of sacrifices to ensure my success. I told him I was on a college break and headed home to visit my parents. That's how he found out I went to Harvard. An approving eye glinted at me in the rearview window, and quickly, we crossed the boundaries of rider and driver. I became his daughter, all grown up—the product of his sacrifice.

    And then came the fateful question: "What do you study?" I answered "history and literature" and the pride in his voice faded, as I knew it might. I didn't even get to add "and African-American studies" before he cut in, his voice thick with disappointment, "All that work to get into Harvard, and you study history?"

    Here I was, his daughter, wasting the biggest opportunity of her life. He went on to deliver the age-old lecture that all immigrant kids know. We are to become doctors (or lawyers, if our parents are being generous)—to make money and send money back home. The unspoken demand, made across generations, which my Uber driver laid out plainly, is simple: Fulfill your role in the narrative(故事) of upward mobility so your children can do the same.

    I used to feel anxious and backed into a corner by the questioning, but now as a junior in college, I'm grateful for their support more than anything. This holiday season, I've promised myself I won't get annoyed at their inquiries. I won't defensively respond with "but I plan to go to law school!" when I get unrequested advice. I'll just smile and nod, and enjoy the warmth of the occasion.