Life may have evolved on at least three planets within a newly discovered solar system 39 light years from Earth. Astronomers at the NASA have discovered no less than seven roughly Earth-sized worlds orbiting a dwarf star in the system. Scientists had previously identified a tiny number of "exoplanets", which are believed to have the qualities needed to support life. However, the new system contains an unprecedented(前所未有) number of Earth-sized, probably rocky planets, and is being acknowledged as an "accelerated leap forward" in the search for extraterrestrial (外星球的)life.

    Three of the new planets are said to be particularly promising because there might exist oceans. Thomas Zurbuchen, associate administrator of NASA, told a press conference in Washington: "This gives us a hint that finding a second Earth is not a matter of 'if', but 'when'."

    The planets were discovered using NASA's Spitzer Space Telescope, which was able to track how fast each of the planets crossed the star Trappist-l and completed an orbit. From this the research team calculated how far the planets were from their star, and therefore how likely they are to be habitable.

    NASA's Hubble Space Telescope is already being used to search for atmospheres around the planets. Future telescopes, including the proposed European Extremely Large Telescope and the James Webb Space Telescope, may be powerful enough to discover markers of life, such as oxygen in the atmospheres of exoplanets.

    Astronomers believe there could be as many as 40 billion potentially habitable worlds in our galaxy, the Milky Way. Prof Zurbuchen said that now was a "gold-rush phase" in the search for these exoplanets.

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    Drive through any suburb in the U.S. today,and it's hard to miss the bins that have become companions to America's trash cans.Recycling has become commonplace,as people recognize the need to care for the environment. Yet most people's recycling consciousness extends only as far as paper,bottles,and cans.People seldom find themselves facing the growing problem of e-waste.

    E-waste rapidly increases as the techno-fashionable frequently upgrade to the most advanced devices,and the majority of them end up in landfills（垃圾填埋地）.Some people who track such waste say that users throw away nearly 2 million tons of TVs,VCRs,computers,cell phones,and other electronics every year.Unless we can find a safe replacement,this e-waste may get into the ground and poison the water with dangerous toxins（毒素）,such as lead, mercury,and arsenic.Burning the waste also dangerously contaminates the air.

    However,e-waste often contains reusable silver.gold.and other electrical materials.Recycling these materials reduces environmental problems by reducing both landfill waste and the need to look for such metals,which can destroy ecosystems.

    A growing number of states have adopted laws to ban dumping e-waste.Still,less than a quarter of this refuse will reach lawful recycling programs.Some companies advertising safe disposal（处置）in fact merely ship the waste to some developing countries,where it still ends up in landfills.These organizations prevent progress by unsafely disposing of waste in an out-of-sight,out-of-mind location.

    However,the small but growing number of cities and corporations that do handle e-waste responsibly represents progress toward making the world a cleaner,better place for us all.

    Henry had been a journalist for many years. He had worked on many international newspapers and magazines and traveled all over the world.

    Henry had witnessed wars and natural disasters such as floods, earthquakes and erupting volcanos(火山爆发). He had reported on serious accidents such as major fires and airline crashes. He had seen every kind of terrible crime and strange event there was. He had met and written about some of the most unusual people in the world. In fact, there wasn't much that Henry had not seen or done.

    Now he was retired from journalism. He owned a very expensive restaurant and spent his days talking to his wealthy and important customers. He liked to say that nothing surprised him.

    One day he was sitting at the bar in his restaurant when a big gorilla walked in and asked for a table. Henry showed no surprise. He took the gorilla to a table and handed him a menu. He treated him politely and pretended there was nothing at all strange about having a gorilla in his restaurant.

    The gorilla looked through the menu and ordered a salad. Henry served the gorilla his salad personally, knowing that his waiters and waitresses would be too frightened. At last the gorilla finished his salad and asked for the bill. Henry wrote out the bill and handed it to the big animal. The gorilla studied it, shook his head sadly, then gave Henry fifty dollars.

    "Thank you", Henry said, and then to make conversation he added, "We don't get many gorillas in this restaurant."

    "At fifty dollars for a salad," the gorilla said, "I'm not surprised."

    Kids are cool to wear blue jeans and T-shirts today. It is fashionable like that. Fashion refers to the styles of dress that are currently popular. Fashion goes beyond just clothes, though. It's important for some people to wear only the latest fashions and styles. For others, though, keeping up with trends isn't that important. The one thing that stays the same with fashion is this: it always changes!

    During the 1960s and 1970s, Hippies made bell-bottomed blue jeans (喇叭裤) popular. Also, in the 1980s, Michael Jackson made parachute pants (降落伞裤)all the fashion. Now try to find these items in today's clothing stores!

    Do you know why fashions change? The answer is probably as simple as the fact that people change. Over time, the new replaces the old People are influenced greatly by popular culture, including athletes, musicians, movies stars, as well as popular films, television shows, books and music. We are also influenced by the fashion industry's advertising.

    The stars of popular culture are always searching for a new angle to maintain (保持) their popularity. Often these new angles come in the form of new clothing or hairstyles. When people see these new styles, they often want to imitate (模仿) their favorite stars. To do so, they seek out the latest fashions to make themselves look like the people they want to imitate. In this way, fashions evolve and change over time.

    Clothes have been used to separate people into groups for many years. Even today, brand-name, clothing that is more expensive than other types of clothing can be used by some people to make themselves different from others.

    Unfortunately, this can often have the effect of distancing certain groups from others. Don't forget that it's always OK to develop your own sense of style that is unique and separate from what the fashion world determines! Stay true to yourself and let your personality - not your clothes - speak for who you are!

    City trees grow faster and die younger than trees in rural forestry, a new study finds. Over their lifetimes, then, urban trees will likely absorb less CO₂ from the air than forest trees.

    As we all know, the earth would be freezing or burning hot without CO₂. However, CO₂ is a greenhouse gas, meaning it traps energy from the sun as/heat. That makes temperatures near the ground rise. Human activities, especially the widespread burning-of fossil(化石)fuels, have been sending extra greenhouse gases into the air. This has led to a rise in average temperatures across the globe.

    Studies had shown forests readily absorb CO₂, but there hadn't been much data on whether city trees grow, die and absorb CO₂ at the same rate as forest trees do. So some researchers decided to find out.

    To figure out how quickly trees were growing, researchers tracked their diameters (the width of their trunks) between 2005 and 2014. A tree's diameter increases as it grows, just as a person's waist size increases as they gain weight. About half the weight of a tree is carbon, research has shown. Most of the rest is water. Over the nine years' tracking, the researchers found city trees absorbed four times as much carbon from the air as forest trees. However, they were twice as likely to die. So over the lifetime of each type of tree, forest trees actually absorbed more CO₂.

    City trees grew faster because they had less competition for light from their neighbors. In a forest，trees tend to grow close together，shading their neighbors. Street trees also benefit from higher levels of nitrogen (氮)in rainwater. Nitrogen helps plants grow. Waste gases from gas-burning cars also contain nitrogen, thus enriching city air with nitrogen. Later, rainwater may wash much of it to the ground. Some street trees may also have better access to water than trees in the country because the underground water pipes can leak.

    Shark attacks not only disturb beach activities, but can affect associated tourist industries. Shark nets are a common solution to preventing shark attacks on beaches, but they cause dangers to sea ecosystems.

    Seeking a cost-effective way to monitor beach safety over large areas, we have developed a system called Shark Spotter. It combines artificial intelligence (AI), computing power, and drone (无人机) technology to identify and warn lifesavers to sharks near swimmers. The project is a cooperation between the University of Technology Sydney and The Ripper Group, which is pioneering the use of drones—called "Westpac Little Ripper Lifesavers"—in the search and rescue movement in Australia.

    SharkSpotter can detect sharks and other potential threats using real-time aerial imagery. The system analyses video from a camera attached to a drone to monitor beaches for sharks, send warnings, and conduct rescues. Developed with techniques known as "deep learning", the Shark Spotter system receives imagery from the drone camera and attempts to identify all objects in the scene. Once certain objects are detected, they are put into one of 16 categories: shark, whale, dolphin, rays, different types of boats, surfers, and swimmers.

    If a shark is detected, Shark Spotter provides both a visual sign on the computer screen and an audible warning to the operator. The operator confirms the warning and sends text messages from the Shark Spotter system to the Surf Life Savers for further action. In an emergency, the drone is equipped with a lifesaving flotation pod (漂浮仓) together with an electronic shark repellent (驱逐装置) that can be dropped into the water in cases where swimmers are in severe trouble, trapped in a rip, or if there are sharks close by.

    In January 2018, the Westpac Little Ripper Lifesavers was used to rescue two young swimmers caught in a rip at Lennox Head, NSW. The drone flew down the beach some 800 meters from the lifeguard station, and a lifesaving flotation pod was dropped from the drone. The complete rescue operation took 70 seconds.

    We believe Shark Spotter is a win-win for both marine life and beachgoers. This unique technology combines dynamic video image processing AI and advanced drone technology to creatively deal with the global challenge of ensuring safe beaches, protecting environments, and promoting tourism.