根据短文理解，选择正确答案。

    You may like chewing gum (口香糖) after meals to stop your breath smelling bad; or your mother might use a special neutralizer (调理剂) to protect her permed hair (烫发). But have you thought about the chemical principles behind such everyday actions?

    On March 2, the Senior 3 students from the IB (International Baccalaureate, 国际文凭) classes at Beijing Huijia Private School presented their discoveries, all in fluent English. This kind of seminar is held every year to show the achievements of the IB chemistry experiment lessons offered by the school. IB is a qualification based on a common curriculum (课程) for students aged 16-18 in any country and is recognized by universities everywhere.

    "Once I saw an advertisement for xylitol (木糖醇) gum," recalled Zhang Xinju. "Suddenly an idea came to my mind: are there any chemical reactions when the xylitol is working on our teeth?"

    Zhang and his partner Bu Xuan visited several hospitals to try and find out. "Doctors know that xylitol can protect teeth, but few could explain how the chemical reactions happen," said the 17-year-old boy.

    Presenting the results of their research in English to an audience of Chinese and foreign judges was never a problem for the students.

    "Textbooks for IB students are in English, and our teachers speak in English," explained Wei Duan and Han Yu, whose research topic was "The Acid-Base Reaction (酸碱反应) in the process of Hair-Perming".

    "In Senior 1 we often referred to Chinese textbooks, but we found we could understand and express it all in English by the second year."

    Lu Jiang, the school's IB chemistry teacher and China's only IB vice-examiner, is proud that her students can apply scientific theories they learn in class to daily life.

    "You might have learned these facts from you kindergarten teachers, but few think about the theories behind them," Lu said. "This kind of practice is intended to develop the scientific thinking they will need in their future studies."

    A survey by an international temporary service agency found that U. S. managers believe that people with a sense of humour do better at their jobs, compared with those who have little or no sense of humour. In fact, about 96 percent of those surveyed said people with a sense of humour do better.

    The survey went on to point out that the results suggest that a sense of humour may help light-hearted employees keep their jobs during tough times. And, what's more, it may push them up the corporate ladder past their humourless colleagues. Why? It seems that those with a sense of humour are better communicators and better team players.

    Studies have shown that happy workers are more productive. In fact, a researcher at California State University found that humour could help the employees to release tension.

    Research done by psychologist Dr. Ashton Trice at Mary Baldwin College in Virginia showed that humour helps us think. When people feel stuck on important projects, they tend to feel angry or depressed.  According to Dr. Trice's research, taking time out to laugh can help us to get rid of negative feelings and allow us to return to a task or move on to another project unaffected by past defeat.

    If humour is really this important, then why don't we use it more often on the job? Most likely, the main reason is that many people are unaware of the positive effects of humour in the workplace. However, it is important to realize that some humour is not suitable for the workplace, and that it is often used at wrong times.

    83-year-old Antonio Vicente has spent the last four decades of his life fighting against the current. As Brazilian landowners cut down rainforests to make room for profitable (盈利的) plantations and cattle grazing grounds, he struggled to bring the thick jungles of his childhood back to life.

    In 1973 Antonio took up the challenge of restoring the forest on a 31-hectare piece of land that had been destroyed for cattle grazing. Ironically enough, he bought the land in Brazil's Sao Paulo region, using credits（贷款）that the military government was giving out to promote deforestation(砍伐森林) and agricultural technology. But Antonio didn't use the money to promote the national agriculture but wanted to revive the forest.

    "You are stupid. Planting trees is a waste of land. You won't have income. If it's full of trees, you won't have room for cows or crops," Antonio's neighbors told him. But he knew the damage caused by deforestation was far greater than financial profit. Antonio had grown up on a rural farm, and watched his father and the other villagers cut down forests at the owners' orders, either for charcoal production or to clear land for grazing cattle. He had watched the ancient water sources dry up and people struggling to survive.

    With only some donkeys and a few hired workers Antonio brought back the forest to his land. What started out as a weekend hobby soon became a permanent way of life. Antonio often recalls spending days and nights in his young jungle, surrounded by rats and foxes, and eating banana for breakfast, lunch and dinner.

    As the forest grew, the water returned, and Antonio says that there are now over 20 water sources on his land that were no longer there when he bought it. Then the animals started making a home there. Today, the forest is alive with sounds of birds and insects living there, and more species are settling in every year.

    What is eBay? The simple answer is that it is a global trading platform where nearly anyone can trade practically anything. People can sell and buy all kinds of products and goods, including cars, movies and DVDs. sporting goods, travel tickets, musical instrument clothes and shoes- the list goes on and on.

    The idea came from Peter Omidyar, who was born in Paris and move to Washington when he was still a child. At high school, he became very interested in computer monogramming and after graduating from Tuft University in 1988, he worked for the next few years as a computer engineer. In his free time he started eBay as a kind of hobby, at first offering the service free by word of mouth.By1996 there was so much traffic on the website that he had to upgrade (升级) and he began charging a fee to members Joined by a friend, Peter Skoll, and in 1998 by his capable CEO, Meg Whitman, he has never looked back. Even in the crashes of the late 1990s, eBay has gone from strength to strength. It is now one of the ten most visited online shopping websites on the internet.

    eBay sells connections, not goods, putting buyer and seller into contact with each other. All you have to do is take an e-photo, write a description fill out a sales form and you are in business; the world is your market place. Of course for each item (商品) sold eBay gets a percentage and that is a great deal of money. Every day there are more than sixteen million items listed on eBay and eighty percent of the items are sold……

    So you're thinking about breaking up with me. But before doing that, make sure you have examined its short-term and long-term environmental effects.

    Let's start simple: consider the great number of gallons of clean, drinkable water that would be wasted by my crying in the shower. Scientists don't have a precise estimate of how much water might be lost, but, considering the length of my listening to the recent two sad albums during the shower, the amount is sure to be catastrophic.

    Make no mistake: running from my sweet hug leaves a set of carbon footprints. Your leaving me will start a swift chain of events that results in me at a bar, drunkenly cursing at you with my friends.

    At the end of the night, I will be forced to take a taxi home instead of the subway. Those extra carbon dioxide releases are a breakup by-product, as are the single-use plastic bottles of Glacier Freeze-flavor Gatorade I'll surely buy the next morning.

    Some effects are more hidden. Should you kick me to the roadside, you must anticipate that I am going to sit there eating ice cream. I will eat ice cream a lot every day, because I have seen sad women do this in movies. This, of course, causes ecological disaster. Not only do dairy cows produce greenhouse gas, but industrial dairy farming can cause the destruction of prairies (北美草原) forests, and other ecosystems. You might meet other interesting women in your life, but good luck is replacing North America's wetlands!

    Breaking up with me is a very personal choice, and no one can make it for you. I only hope that you have gained a helpful new way of thinking, one broad enough to deal with the world that waits for you in your single-hood. There might be "other fish in the sea," but will there be actual fish in the real sea? It doesn't look good. Alternatively, we could stay together and preserve this beautiful blue sea for our grandchildren. The Intergovernmental Panel on Climate Change and I eagerly wait for your decision.

In 2019, after retiring from her career as a social worker, Ane Freed-Kernis decided to build a home workshop and devote all of her free time to stone carving. "I might be covered head to toe in dust but I'm happy—it was something I needed more of in my life when I hit 60," she says.

This appeal has its origins in Freed-Kernis' childhood. Growing up on her father's farm in Denmark, she used to wander through the fields with her eyes fixed on the ground, looking for stones to add to her collection. "I've always been drawn to the shapes and textures（质地）of stones," she says.

After moving to England in 1977 and training as a social worker, Freed-Kernis soon became occupied with her busy career and the demands of raising her son. Stones were the last thing on her mind, until her father died in 2005. "He took a stone carving course in his retirement, and I always thought stone seemed so fun but never had the time to look into it myself," she says. "After he died, I became determined to learn in his honour."

Signing up for a week-long stone carving course at Yorkshire Sculpture Park, Freed-Kernis began to learn how to turn a block of rock into well-designed shapes. "It was really scary at the start because you would spend hours just hammering（锤打）."

Now 65, Freed-Kernis has a thriving small business built largely through word of mouth. She creates 12 to 15 pieces a year that can take anywhere from a few days to three weeks to complete, while her prices range from £200 to £3, 000. "I'm making smaller ones," she says. "I don't have to depend on the money much, so I want to keep prices in the range that people can afford, mainly just covering costs and labour（劳动力）."