In Korea, it is rude to wear shoes inside someone's house because it is considered dirty. In Saudi Arabia, you should not bring food to someone's house because taking food or drink suggests that you think the host cannot afford the meal. More and more people around the world are travelling abroad to study, to go on vacation, or to work, and while it can be a great way to learn about other cultures, there may be times when travelers accidentally annoy their host.

    The same gesture can have very different meanings in different countries. The gesture meaning OK in the United States means something completely different in Brazil as Ella Yao discovered. Ella had travelled to Brazil to study and was living with a host family. During dinner, her host asked Ella if she was enjoying the meal. Because her mouth was full of food, Ella made a sign with her hand that to her meant OK. Although Ella meant the food was good, this symbol in Brazilian culture is extremely rude and her host was deeply annoyed.

    While travelling in Thailand, Elizabeth Brown learned that there are differences in food in the United States and Thailand. She stopped at a small, family-owned restaurant in Chiang Mai and ordered spring rolls. She was really enjoying eating them until she got the last one and noticed that there was an insect inside. She complained to the server. Later, she discovered that although insects are disgusting to most Americans, they are considered a delicacy(佳肴) in some countries.

    All these mistakes can be avoided with some research on cultural differences before you go abroad. However, if you do accidentally annoy someone, quickly apologize, and learn from your mistake.

    We've considered several ways of paying to cut in line: hiring line standers, buying tickets from scalpers (票贩子), or purchasing line-cutting privileges directly from, say, an airline or an amusement park. Each of these deals replaces the morals of the queue (waiting your turn) with the morals of the market (paying a price for faster service).

    Markets and queues—paying and waiting—are two different ways of allocating things, and each is appropriate to different activities. The morals of the queue, “First come, first served, have an egalitarian (平等主义的) appeal. They tell us to ignore privilege, power, and deep pockets.

    The principle seems right on playgrounds and at bus stops. But the morals of the queue do not govern all occasions. If I put my house up for sale, I have no duty to accept the first offer that comes along, simply because it's the first. Selling my house and waiting for a bus are different activities, properly governed by different standards.

    Sometimes standards change, and it is unclear which principle should apply. Think of the recorded message you hear, played over and over, as you wait on hold when calling your bank: “Your call will be answered in the order in which it was received.” This is essential for the morals of the queue. It's as if the company is trying to ease our impatience with fairness.

    But don't take the recorded message too seriously. Today, some people's calls are answered faster than others. Call center technology enables companies to “score” incoming calls and to give faster service to those that come from rich places. You might call this telephonic queue jumping.

    Of course, markets and queues are not the only ways of allocating things. Some goods we distribute by merit, others by need, still others by chance. However, the tendency of markets to replace queues, and other non-market ways of allocating goods is so common in modern life that we scarcely notice it anymore. It is striking that most of the paid queue-jumping schemes we've considered—at airports and amusement parks, in call centers, doctors' offices, and national parks—are recent developments, scarcely imaginable three decades ago. The disappearance of the queues in these places may seem an unusual concern, but these are not the only places that markets have entered.

    Julian Beever is a well-known British artist. His drawings have appeared on the streets of London, Paris, Tokyo, New York and many other cities around the world. Beever creates what looks like a three-dimensional design (三维设计). From animals to heroes to buildings, the paintings are wonders for our eyes to see.

    In his book Pavement Chalk Artist, Beever shares some of his most attractive and humorous pieces. Here are the examples you will find in the book.

    Philadelphia Eagle, created in the USA, is a huge drawing with an eagle (鹰) landing on an American national flag. Meeting Mr. Frog was created in Spain and is about a realistic- looking (样子逼真的) frog sitting on a lily pad (睡莲叶子). Swimming Pool in the High Street is about a woman relaxing in a swimming pool sinking into the middle of the street.

    Along with an introduction about his background, Beever shares information about his time at home in the UK and abroad. With a fun story coming after each piece of art, this 112- page book is really worth another look.

    Technology is always trying to meet our needs and demands. There's a new frontier in 3D printing that's beginning to come into focus: food. Recent development has made possible machines that print, cook and serve foods on a mass scale. And the industry isn't stopping there.

    Food production

    With a 3D printer, a cook can print complicated chocolate sculptures and beautiful pieces for decoration on a wedding cake. Not everybody can do that — it takes years of experience, but a printer makes it easy. A restaurant in Spain uses a Foodini to "recreate forms and pieces" of food that are "exactly the same," freeing cooks to complete other tasks. In another restaurant, all of the dishes and desserts it serves are 3D-printed, rather than farm to table.

    Sustainability (可持续性)

    The global population is expected to grow to 9.6 billion by 2050, and some analysts estimate that food production will need to be raised by 50 percent to maintain current levels. Sustainability is becoming a necessity. 3D food printing could probably contribute to the solution. Some experts believe printers could use hydrocolloids (水解胶体) from plentiful renewables like algae (藻类) and grass to replace the familiar ingredients (烹饪原料). 3D printing can reduce fuel use and emissions. Grocery stores of the future might stock "food" that lasts years on end, freeing up shelf space and reducing transportation and storage requirements.

    Nutrition

    Future 3D food printers could make processed food healthier. Hod Lipson, a professor at Columbia University, said, "Food printing could allow consumers to print food with customized nutritional content, like vitamins. So instead of eating a piece of yesterday's bread from the supermarket, you'd eat something baked just for you on demand."

    Challenges

    Despite recent advancements in 3D food printing, the industry has many challenges to overcome. Currently, most ingredients must be changed to a paste (糊状物) before a printer can use them, and the printing process is quite time-consuming, because ingredients interact with each other in very complex ways. On top of that, most of the 3D food printers now are restricted to dry ingredients, because meat and milk products may easily go bad. Some experts are skeptical about 3D food printers, believing they are better suited for fast food restaurant than homes and high-end restaurants.

    Envelope Budget

    From McDonald's to Sonic, fast food had a bad effect on my waistline and my budget. It was nothing to run to a drive-through to pick up a cold drink or a quick bite to eat. It was so easy to use my card for a small purchase. For me, I got a lot of satisfaction from fast food.

    One day I sat down and calculated that I was spending a surprising $40 a week on fast food. This was a lot of iced coffee and hamburgers! Instead of reducing my guilty pleasures, I decided to give myself a strong budget to reduce my consumption. Every Monday I placed an envelope with $20 in my purse. That was my fast food budget for the entire week. If there was anything left over at the end of the week, it was mine to save or spend. If I spent all of the money during the week, there were no more fast food stops that week.

    The budget made me more mindful of my purchases. Instead of purchasing a large drink from Sonic, I would purchase a small. It was sill satisfying but not nearly as pricey. Instead of eating a whole meal, I would pick the part that I actually wanted. Many days, the thought of hanging onto the money for a special purpose meant more to me than the instant satisfaction of fast food. I never really felt unhappy because it was a conscious choice to spend or save with each purchase.

    Envelope budget kept me honest. I had a clear idea how much money was spent each week on fast food purchases. I started to bring my lunches more often to save more money for the week. It was a fun challenge to see how much I could save every week.

    Changing the way I spent on fast food not only helped my budget, but improved my weight. In the first month I was able to get rid of 5 pounds by simply changing the way I approached spending on fast food. Now I am more likely to bring my lunch than to buy it. I am not upset, but empowered to make positive choices to improve my life.

    It is common to see many different kinds of insects while spending time outside in the summer. Some of them do not trouble people and can even add beauty to the natural environment. Other insects can harm the environment or humans. The population of these insects seems to stay large and healthy.

    But scientists say this does not appear to be true for some flying insects that serve an important purpose. There is growing evidence that these insects are decreasing across the world.

    One researcher looking into the present insect population is Doug Tallamy, a professor at the University of Delaware. He remembers walking through Washington D. C., in the past when it was "alive with insects, especially butterflies". Now, he said, "The flying insects are actually gone." Wilson said this point seemed to be proved during a drive he made last year from Boston to Vermont. He was surprised that, during his trip, he counted only one insect that had hit the car's front window. Several other scientists have carried out similar tests by checking how many insects hit their cars while traveling.

    While researchers admit this method is not scientific, they say it can still help them understand the changing flying insect population. There have not been many studies done on the flying insect populations covering large areas. However, some international research suggests a downward turn. In 2006, a group of studies showed that there had been a 14-percent drop in ladybugs(瓢虫) in the United States and Canada from 1987 to 2006. In Germany, a 2017 study found an 82-percent drop in the number of flying insects compared to levels recorded in 1990.

    After the German study, other countries also started looking into the problem. David Wagner of the University of Connecticut says other evidence leads him to believe the findings of the 2017 study are "clearly not a German thing".