Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. We do know, however, that they existed over 5,500 years ago in ancient Asia.

    The oldest known transport wheel was discovered in 2002 in Slovenia. It is over 5,100 years old. Evidence suggests that wheels for transport didn't become popular for a while, though. This could be because animals did a perfectly good job of carrying farming tools and humans around.

    But it could also be because of a difficult situation. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren't going to be constructed until there was plenty of demand for them. Eventually, road surfaces did become smoother, but this difficult situation appeared again a few centuries later. There had been no important changes in wheel and vehicle design before the arrival of modem road design.

    In the mid-1700s, a Frenchman came up with a new design of road—a base layer (层) of large stones covered with a thin layer of smaller stones. A Scotsman improved on this design in the 1820s and a strong, lasting road surface became a reality. At around the same lime, metal hubs (the central part of a wheel) came into being, followed by the pneumatic tyre(充气轮胎) in 1846. Alloy wheels were invented in 1967, sixty years after the appearance of tarmacked roads (柏油路). As wheel design took off, vehicles got faster and faster.

    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.

    Those accustomed to browsing (浏览) through thousands of books in large bookstores may find Japan's Morioka Shoten a little strange. That's because this tiny bookstore that is located in Ginza, Tokyo sells only a single book at a time.

    Opened in May 2015, Morioka Shoten is the brainchild (脑力劳动成果；发明；主意) of Yoshiyuki Morioka. He began his career as a bookstore clerk in Tokyo's Kanda district before branching out into opening his own store. It was here while organizing book reading and signing that he realized that customers usually came into the store with one title in mind. Morioka began to wonder if a store could exist by selling multiple copies of just one single book. In November 2014, he partnered Masamichi Toyama to establish a unique bookstore with the philosophy of "a single room with a single book".

    The selections that are picked by Morioka change weekly and vary widely to attract customers with different interests. Recent choices include The True Deceiver, an award-winning Swedish novel by Tove Jansson, Hans Andersen's fairy tales, and a collection of Karl Blossfeldt's photography of plants. Morioka has also selected books written by a famous Japanese author Mimei Ogawa.

    To highlight his only offering, Morioka often uses clever tricks. For example, when selling a book about flowers, the storekeeper decorates his shop with the ones that have been mentioned in the book. He also encourages authors to hold talks and discussions so they can connect with customers. Morioka says his goal is to let customers experience being inside a book, not just a bookstore.

    Risky as the idea might seem, things appear to be going well. The storekeeper says he has sold over 2,100 books. Things can get better given that his bookstore is becoming increasingly popular not just among the locals but also visitors from other countries.

    Cold weather during winter months may keep many people from leaving home and running in the open air.

    However, a new study shows that the drop in temperature is a good reason to run. In fact, researchers say, running in cold weather helps improve one's performance.

    Many people say running in the winter can be difficult. Two reasons are the low temperatures and bitter winds. Yet many runners might find it easier than running in hot weather.

    That could be because lower temperatures reduce stress on the body. When you run in cold weather, your heart rate and the body's dehydration (脱水) levels are lower than in warmer conditions. The body needs less water on a cold day than in warm weather.

    This information comes from sports scientists at St. Mary's University in London. John Brewer is a professor of applied sport science at St. Mary's.

    For this study, he and other researchers put a group of people into a room they called an "environmental chamber." The researchers then recreated summer and winter weather conditions in the room. The test subjects were asked to run 10,000 meters under both conditions. Brewer says he and his team recorded biological measurements of the runners.

    "We've got a group of subjects into the environmental chamber, we've changed the conditions to replicate the summer or winter and we've got them to run a 10km under both of those conditions and taken various measurements on each runner while they've been completing their 10km."

    Brewer says every movement runners make produces heat. He explains that one way in which we lose heat is by sweating. The body loses heat through droplets of sweat. He says the body also loses heat by transporting the blood to the surface of the skin.

    It was Sunday, so Dad and I were at the second-hand goods market, looking for tools, appliances(家用电器), and other things that needed cleaning. Some were broken; others, like silver cups, just needed to be cleaned and polished. It was 1974, and the Depression(经济大萧条) was very serious. Dad worked full-time at a factory, but the money wasn't enough. Dad had tried a second job for a while, but he found it was too hard on the family. One day, he had an excellent idea that set me on a lifelong course of making money to support myself. Standing beside a crowded table at the second-hand goods market, I looked over an ancient manual sewing machine. Someone had changed it to run on electric power. It was much older than Mom's machine, but it looked like it had quality and a long life built into it. "Dad!" I called. "This is a beauty!"

    Dad walked over, pulling a cart full of audio equipment, tools, worn-out appliances, and what appeared to be a block of dull kitchen knife." What have you got, Son?" I described what I saw and what I figured I could do to x the beauty up. Dad paid for my discovery, and we headed home.

    Every day after school I worked on the ancient machine, and every night Dad and I sharpened tools and knives, sanded off rust, polished metal, and replaced missing parts from various items. The next Saturday we headed off, as we did every weekend, to that same market, where we sold the treasures we'd purchased the week before—at a tidy profit. My antique beauty brought in more money than anything else, and Dad let me keep every penny.

    Dad's gone now, but I can never thank him enough. Even if we hadn't needed the extra money Dad and I brought in, I wouldn't have traded those weekends for all the picnics or Little League games in St. Louis—not in a million years.

    Many high school students consider a college education useless. Therefore, they choose not to go to college. If you're one of them, think again. Here are some reasons why you should go to college and receive a good education there.

    Schools and universities are the first sources of knowledge. We take that knowledge later on to build our careers after graduation. More knowledge will be gained after you start working, but without an education, that job will not be within easy reach. Knowledge leads to knowledge.

    While limited within the walls of the educational institutions, we openly explore other cultures of the world. We come to know that ours is not the only culture. Other cultures have valuable insights to share, enriching our own. Education also makes us want to travel and interact with various cultures, broadening our horizons.

    When there's a downturn (衰退) in the economy, those who attended college will be more likely to find a new job than those who only finished grade school and have a limited skills set. The more education you have, the more chances you will get to improve the quality of your life as you have a better job and earn a higher salary.

    When you're skillful and knowledgeable, you get to “rub knees” with people of similar backgrounds and tastes. It means a good education leads to excellent networking. Good networking can benefit you a lot in your later life.

    A good education makes you a more interesting person. You can talk about ideas and events instead of just other people and what's on sale in stores. An educated person doesn't gossip, having a preference to discuss ideas and listen to what other people have to say.