Reflecting(回忆) on the past about those decisions or actions that can't be reversed(推翻) and being occupied with thoughts of “What if?” is no way to live. But there are a few things in life I'd probably do differently if I had the chance.

    I once majored in architecture — something I had been crazy about for as long as I could remember — and then I suddenly had a change of heart. I made an appointment with my adviser, and told him I was no longer certain I wanted to pursue a career in architecture.

    “Don't give up on your childhood dream!” “He's right,” I thought. “I should just stick it out and I shouldn't disappoint the little girl who once loved architecture.”

    It was awful. I was agonized, holding on to a childhood dream that had long since faded. When I talked with a friend about it a year later, he asked: “Right now, what do you want to do with your life?” That's when I came to the realization that dreams change over time and that you should give up the childhood dream if it's not what you want as an adult. Luckily, it wasn't too late. After some serious thought, I changed my major to journalism. It wasn't something I had always imagined myself pursuing — but at that moment,  it was what I wanted.

    We grow up, and sometimes our dreams change — and that's perfectly OK. You just need to ask yourself every once in a while, “Is this still what I want?” If the answer is no, move on and start chasing a new one.

    Farah was sitting in the kitchen going over the party list with her mother. The exams were over and Farah wanted to invite her friends for a party.

    “Farah, aren't you going to invite Hafsa?” her mother asked. Hafsa had been her best friend since childhood.

    “Mother, you know I am now a part of Purple Girls Club and we have some rules about people we can be friends with,” Farah answered.

    “Really? And what are the rules?” her mother asked.

    “Well, only very pretty girls can be part of our group. And Hafsa is so, you know, dark.”

    “I cannot believe it.” her mother said angrily.

    As Farah left the kitchen, her father called her from the living room.

    Farah went to her father and paled when she saw the exam report in his hands.

    “Farah, what has happened to your grades? You have failed in Mathematics.” her father said.

    Farah had no answer. The truth was that the activities of Purple Girls Club left her with very little time for studies.

    “Farah, it says that you can take part in supplementary exams(补考). If your grades don't improve then, I'll cancel your trip to Spain.”

    Farah went to her room and called Gina, the leader of Purple Girls Club.

    “Gina, can you help me to complete my notes before the exams?”

    Gina laughed, “Exams? Who cares about exams?”

    One by one, she called her friends in the club but no one seemed to care or wanted to help. Farah knew Hafsa would help her. Farah also knew Hafsa had been hurt by her, but Hafsa said, “If you need any help, just let me know. We can study together till your exams.”

    Next Monday, as two friends entered the school together. Gina called out

    “Farah, you know our rules. You cannot be friends with those who do not belong to our club.”

    “Gina I have a new rule about friendship,” Farah replied.

    “Can I hug you?” community nurse Joyce Jebambula asks with a smile as she welcomes me back to her village. “Of course,” I say as I put my arms around her. It's an unbelievable moment. Just at the height of the outbreak more than a year ago, there was an “avoid body contact” rule here. It's now been removed.

    One of the most challenging parts of reporting this outbreak over the past 18 months is that I haven't been able to touch anyone in the worst-affected countries. When Ebola(埃博拉病毒) survivors described in tears describing losing their families, I had to almost sit on my hands to avoid reaching out to comfort them.

    The outbreak was declared over in Sierra Leone on 7 November. I returned for the celebrations. But despite reaching this long-awaited milestone, all is not well.

    Ibrahim Koroma, 21, clings to (紧紧抓住) his survivor's certificate (证明) outside the home. All 17 of his family are now dead. The certificate is one of his most prized possessions. "He does not pose any risk to the community" it reads.

    Ibrahim tells me how his landlord has allowed him to stay in one of the rooms of his former family home until the end of the year. He says he doesn't know what he'll do after that. He does some part-time work, relying heavily on help from neighbors. His two little sisters and little brother died in the very room where he now sleeps. He says he often lies awake thinking about them, feeling very bad.

    The Ebola outbreak in West Africa was the worst on record. In past outbreaks there had only been a few hundred deaths and a few hundred survivors. It was thought Ebola could live for only three months. But research has now shown it can linger for at least nine months. Scientists are still trying to find how long it could be infectious.

    Most advertising in ancient times was word-of-mouth, that is, people liked something and told others about it. But even then, people advertised by putting inscriptions (题字) on walls, for example to display political slogans and to offer household goods for sale. Also, in Rome and Greece, in ancient times, it was common for people to use papyrus, a kind of paper, to advertise things they had lost or found. The tradition of wall or rock painting as a way of advertising goods is even more ancient.

    Painting developed in the 15th and 16th centuries, and this increased the forms of advertising. Handbills — small printed notices and advertisements — became common. Then, by the 17th century, advertisements started appearing in weekly newspapers in England. In the 19th century mail order catalogues appeared, promoting all kinds of goods.

    Finally, advertisements in the 1960s became more creative and more interesting. Also, they began to draw attention to the 'unique selling points', the USPs of products. These are the qualities that make a product different from competitors' products.

    These days, advertisers have come up with new ways of promoting their products. For example, product placement is now common. This is advertising in TV programmes or films by having a character, preferably played by a famous actor, use a particular product. For example, Tom Cruise's character in the movie, Minority Report, had a computer with the Nokia logo (商标) on it, and his watch was clearly made by Bulgari.

    TV commercials are a very effective medium for advertisers, though these are very expensive. If an organization wants to have a 30-second TV advert during the annual Superbowl game in the United States, they have to pay about $2.5 million.

    Perhaps the most interesting development is the use of famous personalities to endorse (代言) a product. The basketball player, Michael Jordan, endorsed Nike products and wore them while playing.

    Getting well-known personalities to endorse a product can be very expensive, but endorsements certainly increase a product's sales, especially if the personality has a positive image in the eyes of the public.

    The horse I'm riding is named Candy, which is appropriate, taking account of her love for eating. As we go our way down the mountain of Big Bend National Park, Texas, I'm sweating—half due to the hot weather, half due to an effort to stay on the horse. Candy, however, is relaxed and stops to eat cactuses (仙人掌) as she passes. She is used to the dusty trails through hills and canyons(大峡谷) and ignores my attempts to guide her away from her delicious food. Our ride becomes a battle of will, which Candy wins easily. I comfort myself by admiring the views across Big Bend's wide open spaces.

    Texas only national park, Big Bend, extends across 800,000 acres of the Chihuahuan Desert, in the deep southwest of the state right along the border with Mexico. It is named after the U-turn that the Rio Grande River makes here. It has seen a lot of fights. The Spanish, Anglo-American settles, Mexicans, and Apache and Comanche American Indians all fought to rule this place.

    Our group member, Mike, knows every corner of the park and describes it as “sort of a secret place”. Even some Texans don't know about Big Bend, he says. Other local people describe it as a forgotten national park. Compared with the almost five million travellers that descend on the Grand Canyon every year, only 30000 make it here.

    There are six of us in the riding group, all fairly inexperienced, led by tour guides, Linda and Janelle, who keep both us and the horses in line. We trek along the top of an 800-foot mountain, with wide-winged eagles flying beside us. The air is noiseless.

    The park is fantastic for hikes and has a variety of marked walking paths. The walk is a five-mile round trip. While the final stretch is rather steep, the views over giant canyons and plains are worth the effort.

    In many developed countries, people who have high degrees begin to work longer than those who don't. About 65% of American men aged 62－74 with a professional degree are in the workforce (劳动人口), compared with 32% of men who only finish high school. This gap is part of a deepening divide between the well­educated wealthy and the unskilled poor. Rapid technological advance has raised the incomes of the highly skilled while squeezing those of the unskilled. The consequences, for individuals and society, are profound(意义深远的).

    The world is facing an astonishing rise in the number of old people, and they will live longer than ever before. Over the next 20 years the global population of those aged 65 or more will almost double, from 600 million to 1.1 billion. The experience of the 20th century, when greater longevity (长寿) translated into more years in retirement rather than more years at work, has persuaded many observers that this shift (变化) will lead to slower economic growth, while the swelling (渐增的) ranks of pensioners will create government budget problems.

    Policies are partly responsible. Many European governments have abandoned policies that used to encourage people to retire early. Even the better­off must work longer to have a comfortable retirement. But the changing nature of work also plays a big role. Pay has risen sharply for the highly educated, and those people continue to reap (获得) rich rewards into old age because these days the educated elderly are more productive than the preceding (先前的) generation. Technological change may well reinforce (强化) that shift: the skills that complement (补充) computers, from management know­how to creativity, do not necessarily decline with age.