Since Edmund Hillary and Tenzing Norgay climbed Mount Everest, Mount Qomolangma's peak is no longer a lonely place and is turning into a trash heap.

    So far, more than 350 climbers have successfully reached the peak. And they have complained about waiting for hours in the bottlenecks (狭窄路段) on the way to the peak, a situation that isn't just uncomfortable — it's cold and windy up there — but downright dangerous. If bad weather strikes, climbers can and do die.

    As a matter of fact, the dangerous crowds aren't the only problem on Qomolangma. All those climbers need to bring a lot of gear—and much of them ends up being left on the mountain, sometimes even the peak itself. Mount Qomolangma is becoming the world's largest dump. Here's mountaineer Mark Jenkins writing in National Geographic about the state of Qomolangma: “The two standard routes, the Northeast Ridge and the Southeast Ridge, are disgustingly polluted with oxygen cans and torn tents everywhere.”

    But the good news is that some mountaineers are taking it upon themselves to clean up Qomolangma. Mountianeer Paul Thelen and his friend Eberhard Schaaf are part of the annual Eco Everest Expedition, which has been cleaning up rubbish from base camps to the peak since 2008. So far they've collected over 13 tons of garbage.

    Some of that rubbish is even being used for a higher purpose. As part of the Mount Everest 8844 Art Project, a group of 15 artists from Nepal collected 1.5 tons of garbage brought down the mountain by climbers. They've transformed the cans and oxygen tanks—and in one case, part of the remains of a helicopter—into 74 pieces of art that have already gone on exhibition in Nepal's capital. Part of the profit from sales will go to the Everest Peakers Association, which has helped collect tons of rubbish on the slopes of the mountain.

    Maddie Messe, 13, has always loved Temple Run, a mobile game that sends her racing through swamps (沼泽) and forests to outrun a pack of crazed monkeys. What she didn't love was being forced to play as a boy — unless she was willing to buy a female version. “I felt like l was being cheated or misrepresented,” Maddie explains．“Girls are just as capable (有能力的) of running away from monkeys as boys are.”

    So last winter, Maddie researched 50 of the most popular iPhone games. What she found was infuriating：90 percent offered free male characters, but only 15 percent let you play as a female for free.

    Armed with those statistics, Maddie drafted a spirited article and fired it off to several major newspapers. The Washington Post agreed to run the piece, which attracted millions of readers around the globe — including the makers of Temple Run! “We realized she had a point,” says Natalia Luckyanova, the game's co-creator. “It was the kick in the pants we needed to say, ' We should fix it．' So we did.”

    Now you can play Temple Run with a female character for free, but Maddie hopes her campaign inspires something deeper.“If you don't see characters that look like you on TV or in movies or games, speak up! Just do your research first,”says Maddie. “One well-supported argument is much more effective than a million angry complaints.”

    In the fight to conserve tropical rainforests, here's a tool you don't often hear about orange peels. Specifically, 12,000 tons of them, dumped (倾倒) on the land. “You don't usually associate waste treatment with biodiversity benefits, something that's good for the environment.

    Tim Treuer is an ecologist at Princeton University, and he's talking about a unique conservation story. It started in the early 1990s, when an orange juice producer called Del Oro set up a company near the Guanacaste Conservation Area in Costa Rica, a region that contains several national parks and a wildlife protection zone.

    Del Oro needed somewhere to dump the orange peels, and the company also owned forested land next to the parkland that it had no intention of growing crops on. So a deal was struck: if Del Oro donated its forested land, it could dump orange peel waste on degraded(退化的) land within the conservation area. Then a thousand dump trucks' worth of orange peels were lying on the land in 1998. “And within about six months the orange peels had been turned from orange peels into this thick black rich soil.”

    “I couldn't even find the site the first time I saw it.” He couldn't find it because, over 16 years, the orange peel waste had sent the land on a journey to become a vine-choked jungle, with three times the diversity of tree species of the neighboring control plot, richer soil and a much thicker covering. In other words, the experiment was a success. The results appear in the journal Restoration Ecology.

    Treuer says perhaps this lesson could be applied elsewhere. “It's a shame that we live in a world with nutrient-limited degraded ecosystems and also nutrient-rich waste streams. We'd like to see those things come together a little bit. That's not license for any agricultural company to just start dumping their waste products on protected areas, but it does mean that land managers, people involved with industrial-scale agricultural operations should start thinking about ways to do thoughtful experimentation to see if in their particular system they can have similar win-win-win results.”

    How to fight California's wildfires? It's an “all of the above” respond.

There might, indeed, be a need to make it easier to thin dying or dead trees out of thickly forested areas, reducing the fuel for wildfires. But the problem is actually more complicated. Even if dead trees are removed, the dry bushes act like kindling (引火物) when wildfires spread.

    Even more to the point, thick forests were not a factor in these recent California's fires. “They're using these fires to talk about forest management that has nothing to do with the landscape in which the fires are occurring,” says Chur Miller. W. M. Keck Professor of Environmental Analysis and History at Pomona College in Claremont, California.

    Climate change is making wildfires worse. The resulting unpredictable weather patterns have created shorter, wetter winters in California, producing a sudden, heavy growth of brushes, grasses and trees. After winter, the state's ongoing drought and record- high summer temperatures draw water out of the plants, making them near-perfect kindling. With the hot and dry Santa Ana winds of fall, fires explode out of control.

    Yet these tragedies can't be blame only on global warming. Wildfires are actually a vital of the state's ecosystem. Lodgepole pines (松树), for example, grow well in fire-prone areas where millions of structures have been built in rural areas of California since the 1940s.When they bum, the cost in lives and treasures skyrockets.

Answering these disasters with a one-dimensional solution helps no one, although it might score short-term political points. The proper response includes placing limits on residential expansion into wildlands; better management and removal of dry brushes and continuously addressing the growing concern of climate changes.

    In other words, the solution isn't either/or. It's all of the above.

    It's school time again! You're probably feeling excited and maybe a little sad that summer is over. Some kids feel nervous or a little scared (害怕的) on the first day of school because of all the new things: new teachers, new friends, and even a new school. Luckily, these "new" worries only stick around for a little while. Let's find out more about going to a new school.

    Most teachers kick off the new school year by introducing themselves and talking about all the stuff you'll be doing that year. Some teachers give students a chance to tell something about themselves to the rest of the class, too. When teachers do the talking on the first day, they often go over classroom rules and school rules so you'll know what's allowed and what's not. Please pay close attention.

    You might already know a lot of people in your classes on the first day, but it's a great day to make new friends, so try to say hello to kids you know and new ones that you don't. Make the first move and you'll be glad, and so will your new friends!

    Seeing friends you haven't seen in a while can make the first day a good one. You can make the day feel special by wearing clothes that you really like. Maybe you got a great T-shirt on one of your vacations, or a pair of sneakers (运动鞋). It also can make you feel good to be prepared and have all the things you need, such as pencils, folders, and whatever else you'll be needing. But make sure that you pack them the night before in case you don't have time in the morning.

    Alexa is a form of artificial intelligence, or Al for short. Many people start their mornings by asking Alexa for the weather forecast or the latest news. A device (设备)that houses Alexa can also play music from your favorite playlists, keep a shopping list, order takeout food, answer questions, send voice messages and even run "smart" home controls.

    Training AI systems to respond to problems with human-like intelligence—and learn from their mistakes —can take months, or even years. Consider Alexa and similar software, such as Apples Siri. To do the tasks its human owners ask, these systems must make sense of and then respond to sentences such as, "Alexa, play my Ed Sheeran playlist" or "Siri , what is the capital of India?"

    Computers can't understand language as it is spoken by people. So AI researchers must find a way to help humans communicate with computers. The technology used to get computers to "understand" human speech or text is known as natural language processing. By natural language, computer scientists refer to the way people naturally talk or write. To teach an AI system a task like comprehending a sentence or responding to a person's last move in a board game, scientists need to feed it lots of examples.

    AlphaGO is an AI system designed by Google that has beaten a human champion, Lee Sedol, at the strategy(策略)board game Go. To train AlphaGo, Google had to show it 30 million Go moves that people had made while playing the game. Then AlphaGo used what it learned to analyze those plays as it played against different versions (版本)of itself. During this practice, the program came up with new moves —ones never seen in games between people.

    Computers, software and devices that are powered by AI can do much more, however, than just play board games and music. And one day they could make our life much easier and much more interesting.