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    How often do you check your phone? According to a study led by Nottingham Trent University in Britain, the average person looks at their phones 86 times a day. Updating their status on social media platforms also made people reach for their electronic companion frequently.

    Even the participants thought that was a lot: this figure is twice as often as they thought they did. Our phones might be shaping our behavior more than we realize. Do you actually look at your surroundings more than at your phone? Is it rude to check your phone when someone is talking to you?

    Sherry Turkle interviewed hundreds of college students about this. She's a professor of social studies at the Massachusetts Institute of Technology. They talked about something they called "the rule of three".

    The rule has to do with being considerate to others despite the allure (诱惑力) of the little flat box. Turkle explains: "If you go to dinner with friends, you don't want to look down at your phone until you see that three people are looking up in the conversation. So there's a new rule where you don't look down unless three people are looking up in order to keep a little conversation alive."

    Actually, if you are clever enough you might use your phone as a tool to connect with people next to you. Sharing a bit of your life with them can bring you closer together. And you can also invite everyone to take a selfie (自拍照) with you.

    But the best thing to deal with mobile phone addiction is to go cold turkey and leave the machine behind occasionally or just switch it off and keep it firmly in your pocket for a while.

    Argentina in the late nineteenth century was an exciting place. Around 1870, it was experiencing an economic boom（繁荣）, and the capital, Buenos Aires, attracted many people. Farmers, as well as a flood of foreigners from Spain and Italy, came to Buenos Aires seeking jobs. These jobs didn't pay well, and the people felt lonely and disappointed with their new life in the city. As the unhappy newcomers mixed together in the poor parts of the city, the dance known as the tango(探戈舞) came into being.

    At the beginning the tango was a dance of the lower classes. It was danced in the bars and streets. At that time there were many fewer women than men, so if a man didn't want to be left out, his only choice was to dance with another man so that he could attract the attention of the few available women. Gradually, the dance spread into the upper classes of Argentinean society and became more respectable.

    In Europe at this time, strong interest in dance from around the world was beginning. This interest in international dance was especially evident in Paris. Every kind of dance from ballet(芭蕾舞) to belly dancing could be found on the stages of the Paris theaters. After tango dancers from Argentina arrived in Europe, they began to draw the interest of the public as they performed their exciting dance in cafes. Though not everyone approved of the new dance, saying it was a little too shocking, the dance did find enough supporters to make it popular.

    The popularity of the tango continued to grow in many other parts of the world. Soldiers who returned to the United States from World War I brought the tango to North America. It reached Japan in 1926, and in 2003 the Argentinean embassy(大使馆) in Seoul hired a local tango dancer to act as a kind of dance ambassador, and promote tango dancing throughout South Korea.

    People who do not get enough vitamin A in their diet may develop night blindness. But in the developing world, a lack of vitamin A causes much more serious harm to children. The world Health Organization links the lack of vitamin A to as many as 250,000 child deaths every year.

    One excellent source of vitamin A is found in newly developed sweet potatoes with orange flesh. Orange sweet potatoes contain high levels of beta-carotene, which the body changes into vitamin A. Experts say orange sweet potatoes could help the Africans who are lacking in vitamin A. But, first, more people will need to be persuaded to eat them. Sweet potatoes need a better image in Africa. Jan Low with the International Potato Center says, “We do have an image problem with sweet potatoes. In many African countries, they are seen as a crop of the poor.”

    Ms. Low explains that sweet potatoes are mainly grown by poor women to feed their families in case another crop fails. The sweet potatoes commonly grown in Africa have white or yellow flesh. But they are low in vitamin A.

    Jan Low took part in a project to study how to market orange sweet potatoes to Africans best. She worked on an information campaign(活动) in Mozambique and Uganda. The campaign included radio messages about the nutritional(营养的) benefits of the orange sweet potato. They advertised its ability to “fight diseases, make you strong, clear you skin and make you look healthy”. In areas without radio, the campaigners spread the message through theater. The performances included singing, dancing and storytelling. And everywhere they went, the campaigners wore orange T-shirts and hats. They even drove orange cars.

    Dan Gustafson heads the Washington office of the United Nations Food and Agriculture Organization. He mentions the efforts in the past to increase the popularity of other nutritious crops. He says most of these efforts failed because organizers of the campaigns did not consider what people wanted to eat. People want to eat what they are familiar with. But Mr. Gustafson sees a better chance for the efforts to increase the popularity of the orange sweet potato in Africa. Except for the color, the orange sweet potato is almost the same as what people already eat. Dan Gustafson says, “I think this time the campaigners will succeed, because they have made enough advertisements and the difference between the vegetable they have advertised and what people already eat is not a radical one.”

    After some blood tests, Dr Stubs stood before me, a tall man, but short on personality and sporting a cold expression. You have systemic lupus, he said matter-of-factly. "Lupus," he continued, "is an auto-immune disease and …." I remember certain details but mostly I remember him talking about children. "Children are no harm. But childbirth would jumpstart additional symptoms that could be life threatening. You already have two kids anyway."

    As I got up to leave, shaken and drained, he said his parting words, "I would discourage any further research. There is no cure and nothing can prevent its progression."

    Still, I did research lupus and its symptoms tiredness and joint pain-were both consistent with what I was experiencing. And eventually some major organs could be affected, causing shutdown and possibly death.

    I studied and found out that echinacea had a record in making immune system stronger. I decided that along with the plant I would strengthen my mindset by immersing myself in my family with my one-year-old son and three-year-old daughter.

    After another visit, I decided never to go back to Dr. Stubs. How could one endure repeatedly hear desperately words coming from an emotionless mouth even though they were truth? The years passed. When I would feel tired and achy I pulled support from my children and their laughter.

    Finally, after eight years, I went to Dr. Kirstein who was recommended by a friend. She stood there holding my hand and looking into my eyes warmly.

    "So let's talk a little

    Instantly my defenses were down. Before I knew it, she had me running on and on about my children, my husband, my life and dreams. I told her about all the meaningful activities I was involved in, those things I might have never done without the disease.

    After several follow-up tests, and greater research into my family history, Dr. Kirsteincame to conclusive answer. I did not have systemic lupus. There must be something wrong with the initial tests 8 years before.

    I didn't know whether I should jump for joy or scream because I had been living the last eight years in fear of a fatal disease. But then I realized that I had been living every day, not so much in fear, but happiness Even day was a gift and I knew it.

    Janus, the Roman god, has two faces looking in opposite directions. So does artificial intelligence (AI). On one side are the positive changes, enabling people to achieve more, far more quickly, by using technology to improve their existing skills. Look the other way, though, and there are plenty of potential pitfalls.

    Like Janus, technological change may also cause disruption(混乱), but AI is likely to have a bigger impact than anything since the appearance of computers, and its consequences could be far more disruptive.

    In the years ahead, AI will raise three big questions for bosses and governments. One is the effect on jobs. Although CEOs publicly praise the broad benefits AI will bring, their main interest lies in cutting costs. One European bank asked Infosys to find a way of reducing the staff in its operations department from 50,000 to 500. The McKinsey Global Institute estimates that by 2030 up to 375m people, or 14% of the global workforce, could have their jobs replaced by AI.

    A second important question is how to protect privacy as AI spreads. The internet has already made it possible to track people's digital behavior in minute detail. AI will offer even better tools for businesses to monitor consumers and employees, both online and in the physical world. Consumers are sometimes happy to go along with this if it results in personalised service or promotions. But AI is bound to bring invasion of privacy that is seen as unacceptable. For example, law-enforcement officials around the world will use AI to spot criminals, but may also monitor ordinary citizens.

    The third question is about the effect of AI on competition in business. A technology company that achieves a major breakthrough in artificial intelligence could race ahead of rivals, put others out of business and lessen competition. This is unlikely to happen in the near future, but if it did it would be of great concern.

    It is too early to tell whether the positive changes brought by AI will outweigh the risk. But it will put an end to traditional ways of doing things and start a new era for business and for the world at large.

    Sales of Apple's new iPhone 11 in China began on Friday, but were met with a cooler welcome from customers than in previous years. Unlike in previous years, no long lines were seen outside Chinese shops on Friday for the new iPhone, and the product release (发布) only made the headlines in a few media.

    Huawei released its Mate 30 smartphone series on Thursday night. Its new devices(设备) have won consumers' hearts at home and abroad. Many compared it with Apple's new iPhone 11, saying that beats the new iPhone because of innovation and quality. One customer named Zhao Kai, an IT specialist who pre-ordered a Mate 30 Pro on Friday, said that he chose Mate 30 without hesitation. Zhao said, "It's clear that Huawei's new phone with its advanced 5G mode would lead the future global telecommunications market, too."

    In contrast with iPhone 11's poor sales, Chinese netizens (网民) have joined in discussions on Mate 30 and iPhone 11. An online poll on the Mate 30 and iPhone 11 on Weibo on Friday showed that more than 60 percent of netizens chose the Mate 30, while less than 20 percent chose the iPhone 11. Many chose Huawei as a result of its technology.

    Overseas customers also joined in the heated discussions on Huawei's new flagship devices on sites. On Twitter, many netizens said "nice", "best phone ever" and "my favorite one" on Huawei's Twitter account. Some netizens in countries like the UK, the Netherlands and Argentina asked when Huawei's new devices would be released in their countries.