I can't think of a better way of appreciating a new culture than by taking part in one of its festivals. You'll find that some festivals are celebrated by an entire country, while others may be known only to a single city or region, but either way festivals play an important role in a certain culture. Just enjoy them!

★ Tomatina — Bunol, Spain

    Every last Wednesday in August, the town of Bunol is filled with tons of tomatoes in the world's biggest food flight. Many people wear goggles (护目镜) during this hour of great fun, as the town becomes a red river.

★ Boryeong Mud Festival — Boryeong, South Korea

    For two weeks in July, millions gather in Boryeong to experience the grey pools and slides. What began as a way to help sell the region's mineral-rich mud has turned into a festive party with music and fireworks. The mud is usually only available in cosmetic products (化妆品), but here you can cake yourself in grey as you want.

★ Holi — India

    Holi, the Festival of Colors, is a Hindu celebration full of joy and one of India's most important holidays. During the day of the last full moon of the lunar month, usually late February or early March, the air is full of brightly colored powder (粉末). The festival is celebrated differently throughout the country, with bonfires and music, but the cheerful spirit is common among Hindu people around the world.

★ International Pillow Fight Day — Worldwide

    Tens of thousands of people took part in the 4th annual International Pillow Fight Day on April 2, 2013. From London to Vancouver to many other cities, the festival is held in more than 100 countries. So just bring a soft pillow in early April, and watch feathers fly.

    There is a common belief among parents that schools are no longer interested in spelling. No school I have taught in has ever considered spelling unimportant as a basic skill. There are, however, quite different ideas about how to teach it, or how much priority(优先) it must be given over general language development and writing ability. The problem is, how to encourage a child to express himself freely in writing without holding him back with spelling.

    If spelling becomes the only point of his teacher's interest, clearly a bright child will be likely to "play safe". He will write only words within his spelling range(范围). That's why teachers often encourage the early use of dictionaries and pay attention to content rather than technical ability.

    I was once shocked to read on the bottom of a sensitive piece of writing about a personal experience: "This work is terrible! There are far too many spelling mistakes." It may have been a sharp criticism(批评) of the pupils technical abilities in writing, but it was also a sad thing for the teacher who had omitted to read the composition, which contained some beautiful expressions of the child's deep feelings. The teacher was not wrong to draw attention to the mistakes, but if his priority had centered on the child's ideas, an expression of his disappointment with the presentation would have given the pupil more hope to seek improvement.

    Cultural rules determine every aspect of food consumption. Who eats together defines social units. For example, in some societies, the nuclear family is the unit that regularly eats together. The anthropologist Mary Douglas has pointed out that, for the English, the kind of meal and the kind of food that is served relate to the kinds of social links between people who are eating together. She distinguishes between regular meals, Sunday meals when relatives may come, and cocktail parties for relatives and friends. The food served symbolizes the occasion and reflects who is present. For example, only snacks are served at a cocktail party. It would be inappropriate to serve a steak or hamburgers. The distinctions among cocktails, regular meals, and special dinners mark the social boundaries between those guests who are invited for drinks, those who are invited to dinner, and those who come to a family meal. In this example, the type of food symbolizes the category of guest and with whom it is eaten.

    In some New Guinea societies, the nuclear family is not the unit that eats together. The men take their meals in a men's house, separately from their wives and children. Women prepare and eat their food in their own houses and take the husband's portion to the men's house. The women eat with their children in their own houses. This pattern is also widespread among Near Eastern societies.

    Eating is a metaphor that is sometimes used to signify marriage. In many New Guinea societies, like that of the Lesu on the island of New Ireland in the Pacific and that of the Trobriand Islanders, marriage is symbolized by the couple's eating together for the first time. Eating symbolizes their new status as a married couple. In U.S. society, it is just the reverse. A couple may go out to dinner on a first date.

    Other cultural rules have to do with taboos against eating certain things. In some societies, members of a family group, are not allowed to eat the animal or bird that is their totemic ancestor. Since they believe themselves to be descended from that ancestor, it would be like eating that ancestor or eating themselves.

    There is also an association between food prohibitions and rank, which is found in its most extreme form in the caste system of India. A caste system consists of ranked groups, each with a different economic specialization. In India, there is an association between caste and the idea of pollution. Members of highly ranked groups can be polluted by coming into contact with the bodily secretions, particularly saliva(唾液),of individuals of lower-ranked castes. Because of the fear of pollution, Brahmans and other high-ranked individuals will not share food with, not eat from the same plate as, not even accept food from an individual or from a low-ranking class.

    As global temperatures rise, trees around the world are experiencing longer growing seasons, sometimes as much as three extra weeks a year. All that time helps trees grow faster. For the past 100 years, trees have been experiencing fast growth in temperate regions from Maryland to Finland, to Central Europe, where the growth rate of some trees has even sped up nearly 77% since 1870. Assuming wood is just as strong today, those gains would mean more timber(木材) for building, burning, and storing carbon captured from the atmosphere. But is wood really as dense as it used to be?

    Hans Pretzsch, a forest scientist at the Technical University of Munich in Germany, and his colleagues wanted to find an answer. They carried out a study of the forests of Central Europe. They started with 41 experimental plots in southern Germany, some of which have been continuously monitored since 1870. Pretzsch and his team took core samples from the trees—which included Norway spruce, sessile oak, European beech, and Scots pine—and analyzed the tree rings using a high-frequency probe.

    They found that in all four species, wood density has decreased by 8% to 12%, they report online in Forest Ecology and Management. “We expected a trend of the wood density like this, but not such a strong and significant decrease,” Pretzsch says. Increasing temperatures, and the faster growth they spur, probably account for some of the drop. Another factor, Pretzsch says, is more nitrogen in the soil from agricultural fertilizer(化肥) and vehicle exhaust. Previous studies have linked increased fertilizer use to decreased wood density. Above all, the study suggests that the higher temperatures—combined with pollution from auto exhaust and farms—are making wood weaker, resulting in trees that break more easily and wood that is less durable.

    “I am getting worried,” says Richard Houghton, an ecologist at the Woods Hole Research Center in Falmouth, Massachusetts, who was not part of the new study. As the density of the samples dropped, so did their carbon content, by about 50%. That means forests may suffer more damage from storms and may be less efficient at soaking up the greenhouse gas carbon dioxide (CO2) than scientists had thought, Houghton says.

    Here is a record of the discussion about AI (artificial intelligence) conducted by several scientists.

    Scientist A: I would say that we are quite a long way off developing the AI, though I do think it will happen within the next thirty or forty years. We will probably remain in control of technology and it will help us solve many of the world's problems. However, no one really knows what will happen if machines become more intelligent than humans. They may help us, ignore us or destroy us. I tend to believe AI will have a positive influence on our future lives, but whether that is true will be partly up to us.

    Scientists B: I have to admit that the potential consequences of creating something that can match or go beyond human intelligence frighten me. Even now, scientists are teaching computers how to learn on their own. At some point in the near future, their intelligence may well take off and develop at an ever-increasing speed. Human beings evolve biologically very slowly and we could be quickly substituted. In the short term, there is the danger that robots will take over millions of human jobs, creating a large underclass of unemployed people. This could mean large-scale poverty and social unrest. In the long term machines might decide the world would be better without humans.

    Scientists C: I'm a member of the campaign to Stop Killer Robots. Forget the movie image of a terrifying Terminator stamping on human skulls and think of what's happening right now: military machines like drones, gun turrets and sentry robots are already being used to kill with very little human input. The next step will be autonomous “murderbots” following orders but finally deciding who to kill on their own. It seems clear to me that this would be extremely dangerous for humans. We need to be very cautious indeed about what we ask machines to do.

    Judy Wright and her husband decided to move closer to their son, Chris, who lived in Georgia. About a month after the move, Judy fell ill, suffering from her ongoing (不间断的) battle against Parkinson disease.

    Her condition worsened rapidly and she required medical care at home. The family hired a nursing aid who canceled at the last minute. Instead, a woman named TunDe Hector showed up in her place.

    One day, TunDe shared a story with Judy and her family. She remembered a particularly difficult day in 2014, when a stranger had helped her with a kind gesture. She had run out of gas, and with only $5 in her pocket, was walking to a gas station. A man saw her walking and turned his car around. He paid for her gas and gave her all the cash left in his wallet. Upon hearing the story, Judy's son, Chris, took off his hat and said, "That was me!" He was the stranger that had helped TunDe on that difficult day.

    During the care of Judy, the Wright family learned about TunDe's family and her own dream. The nursing aid, TunDe hoped that one day she could become an OB-GYN nurse. Her tuition was past due (逾期) and she had a family to care for, but she was determined to achieve that goal for herself and her family.

    Judy died on July 9,2017. Instead of flowers, her family asked mourners (悼念者) to donate to TunDe's education, to assist her in paying for her nursing school. In less than a week, they raised more than $8,000 and presented her with the surprise check.