Studies show that older people tend to remember the positive things in life rather than the negative things, while younger people remember the positive and negative equally well. The dominant psychological theory to explain this is that older people are aware of their limited time left, so they prioritize positive emotional experiences. But about a decade ago, I worked with biologist Robert Trivers on his idea that there was an evolutionary basis for older people's increased positive outlook. Our research took us in the fascinating direction of exploring how the body uses its energy.

    When our ancestors needed more energy than usual, perhaps while being chased by a tiger, they had to get that energy from somewhere in the body. Could they borrow it from the brain? That organ uses 20 percent of our metabolic (新陈代谢) output, whether we are solving math problems or watching television reruns. Due to this constant energy requirement, borrowing energy from the brain when our need surpasses the available supply is not an option. Perhaps we could borrow energy from our muscles. Because we use far more muscle energy when we are active than when at rest, in principle, we could borrow energy when we are sitting. But the problem is that most of the energy-demanding emergencies of our ancestors required a muscular response. There was no way to borrow energy from our muscles during an emergency because relaxing when a tiger showed up was not an effective response. This brings us to our immune system, which, when strong, protects us from many illnesses and diseases. Like the brain, the immune system works at great metabolic cost, but largely in the service of keeping us healthy in the future. We have an enormous number of immune cells coursing through our body, a momentary break from production is fine. So, when our body needs extra energy, one of the places it goes is our immune function. When you're being chased by a tiger, you don't need to waste energy making immune cells to fight off tomorrow's cold. What you need is to shift all available energy resources to your legs, with the hope that you will live to experience another cough or sneeze.

    As a result, our immune system evolved to run in maximum amounts when we're happy, but to slow down dramatically when we're not. With this background in mind, Trivers supposed that older people evolved a strategy of turning this relationship on its head, becoming more focused on the positive things in life in an effort to enhance their immune functioning. This was helped along by their knowing much more about the world than younger adults, so they can deal with some of the unpleasant things in life more easily.

    For Canaan Elementary's second grade in Patchogue, N.Y., today is speech day, and right now it's Chris Palaez's turn. The 8-year-old is the joker of the class. With shining dark eyes, he seems like the kind of kid who would enjoy public speaking.

    But he's, nervous. "I'm here to tell you today why you should … should…"Chris trips on the "-ld," a pronunciation difficulty for many non-native English speakers. His teacher, Thomas Whaley, is next to him, whispering support."…Vote for …me …"Except for some stumbles, Chris is doing amazingly well. When he brings his speech to a nice conclusion, Whaley invites the rest of the class to praise him.

    A son of immigrants, Chris stared learning English a little over three years ago. Whaley recalls(回想起)how at the beginning of the year, when called upon to read, Chris would excuse himself to go to the bathroom.

    Learning English as a second language can be a painful experience. What you need is a great teacher who lets you make mistakes. "It takes a lot for any student," Whaley explains, "especially for a student who is learning English as their new language, to feel confident enough to say, 'I don't know, but I want to know.'"

    Whaley got the idea of this second-grade presidential campaign project when he asked the children one day to raise their hands if they thought they could never be a president. The answer broke his heart. Whaley says the project is about more than just learning to read and speak in public. He wants these kids to learn to boast(夸耀)about themselves.

    "Boasting about yourself, and your best qualities," Whaley says, "is very difficult for a child who came into the classroom not feeling confident."

    Florida is a state located in the southeastern region of the United States. It is one of the most visited states in the country and the sunshine state attracts millions of visitors each year. Are you planning a vacation to it? Here our travel guide may help you.

    La Nouba at Walt Disney World Resort

    Duration: 90 minutes

    Location: Orlando, Florida

    While you're in Orlando, spend a day at the theme parks with a Cirque du Soleil show at Downtown Disney, La Nouba is the meeting of two different worlds—the fantastic world of the circus (马戏团) people who wear bright colors and the boring world of the people living in big cities who wear dark, lifeless clothes.

    Kennedy Space Center

    Duration: Flexible

    Location: Orlando, Florida

    Spend a day exploring the attractive Kennedy Space Center, just 45 minutes from Orlando. Learn about the history of the US space program and watch beautiful IMAX films. Don't miss the chance to walk under a Saturn V rocket, and experience a real moonwalk!

    Sea World Orlando

    Duration: Varies

    Location: Orlando, Florida

    Spend a day at Sea World Orlando and come face to face with the ocean's most attractive sea animals. With several up­close meetings with killer whales, sharks and turtles, you'll feel the energy and excitement of all kinds of sea life.

    South Beach Cultural Food and Walking Tour

    Duration: 2 hours and 30 minutes

    Location: Miami, Florida

    On the South Beach Cultural Food and Walking Tour, you'll explore the Art Deco district of South Beach on foot and along the way, you'll taste a variety of foods that make South Beach such an internationally well­known food region.

    Price information：

    Click the link below to check price information on your preferred travel date. Our price is constantly updated.

Young Americans Are Less Wealthy Than Their Parents

    The cost of living in the United States is going up, notes writer Alissa Quartz. As is reported in New York Post, Quartz points to "the costs of housing, education and health care in particular." At the same time, a new study, the report of which is called "The Fading American Dream" found that half of Americans born in the 1980s are falling behind their parents economically.

    These findings show that many younger adults are experiencing "downward mobility." In other words, they are not doing as well economically as their parents were at the same age. The idea of downward mobility is especially troubling for Americans, writes Robert Samuelson in The Washington Post. He says most U.S. citizens believe that, over time, the amount of money they earn will rise and life will get easier.

    Alissa Quartz wrote a book about the financial difficulties of Americans. In the book, Quartz tells about teachers who are struggling to pay for regular costs. One high school teacher drives for ride sharing service Uber at night to earn more money. He corrects students' papers between riders.

    A college professor turned to government assistance to feed her child and pay for a doctor. Quartz says even lawyers increasingly cannot earn an income that enables them to meet their needs. The problem of decreasing incomes in their field is made worse by debt they may have from law school. Quartz and the economists who studied these issues say many things have led to lower incomes and downward mobility. The economic recession(衰退) of 2007 to 2009 is partly to blame, they say. Modern technology also plays a part. Quartz says robots threaten to reduce the earnings of health care workers, reporters, and people who work at supermarkets, drug stores and tax preparation services. In The Washington Post, Robert Samuelson noted that poor schools, a weak housing industry and too many government rules are also to blame.

    With all these things, and more, partly responsible, what is the solution? These experts say the answer is complex. But all point to one issue that needs to be examined: economic inequality. Quartz writes that while America is one of the richest countries in the world, it also has one of the biggest divides between the wealthy and the poor.

    The researchers in "The Fading American Dream" study make a similar observation. They say raising GDP will not significantly improve the economic situation of most Americans. A higher GDP may help only those who are already doing well. Instead, the economists say, the United States could try to repeat something Americans born in the 1940s experienced. As those children grew up, they almost all benefited from a better economy.

    My topic today is the Internet. It was prompted(引出)by the first letter, which I am unable to answer fully for the reasons given!

    Dear David, I am a middle school student. Now I am preparing for a writing competition. Could you please check the mistakes in my article about using the Internet and give me some advice? Thank you.

    No name

    David writes: I am very sorry to say that I think it would be very unfair for me to help you win a competition — unfair to the other competitors!

    But I will say that your article is very interesting and I wish you good luck. Your article makes some good points that deserve talking about in this column!

    Dear David,

    I'm now learning English by myself. Can you introduce some useful websites where I can make friends with foreigners? Please help me.

    Moonlight

    David writes: Well, dear moonlight, I bet you made a good choice by using the Net in your self-studies. Two very good websites I would suggest to you are: www.britishcouncil.org.cn and www.britishcouncil.org /learnenglish.

    By the way, for those readers interested in the teaching of English, there is an Internet discussion group called ELTCSChi-L (English Language Teaching Contacts Scheme China List).And also, a healthy warning to all my readers: If over-used, the Internet can be a WOMBAT-A Waste of Money, Brains and Time!

Gottfried Wilhelm von Liebniz was a philosopher and mathematician in search of a model. In the late 1600s Leibniz decided there was a need for a new, purer arithmetic than our common decimal (十进制) system. He got his inspiration from the 5000-year-old book that is at the heart of Chinese philosophy: the I-Ching, or Book of Changes.

This ancient text was such an influence on Liebniz that he titled his article on the new arithmetic "Explanation of a new arithmetic and the ancient Chinese figure of Fu X". Fu Xi was the legendary first author of the I-Ching. The arithmetic that Liebniz described was binary (二进制) code, which is used in almost every modern computer, from iPhones to China's own Tihane-2 supercomputer.

To figure out what Liebniz learned in the I-Ching, we need to understand something that most of us have taken for granted. When we listen to an MP3, look at a digital photo or watch the latest TV drama, we are experiencing a digital representation of reality. That representation is basically just a string of binary signals that are commonly known as 1s and 0s. What Liebniz's gained from the book was that even the most complex reality could be represented in the binary form as 1s and 0s.

In the philosophy of the I-Ching, reality is not entirely real. It is something more like a dream. This dream of reality arises from the binaries of Yin and Yang, as they play out countless combinations, practically everything in the universe. It's not surprising then, from the l-Ching's perspective, that anything in the dream of reality can be represented in a string of 1s and 0s, processed by a computer.

The I-Ching was far more ambitious than the current practical applications of binary code. It is claimed that the I-Ching represents nothing less than the basic situation of human life itself. As a system for predicting the future, the I-Ching might disappoint, but as a way of questioning your own unconscious mind, it can be remarkably useful.

The I-Ching's teachings also contain warnings about our digital revolution. Binary code, powered by modern computers, has an amazing capacity to represent reality. However, the ancient authors of the I-Ching might have understood its potential-and its dangers-even better than we now do.

So when scientific thinkers ask whether computers can create "virtual realities" or "artificial intelligence", they are missing the point. Of course, we can create ever deeper and more complex layers of the dream of reality. The real question is, can we wake up from the dream we're in already?