Dujiangyan is the oldest man-made water system in the world, and a wonder in the development of Chinese science. Built over 2,200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6,000 square kilometres of farmland, take away floodwater and provide water for 50 cities in the province.

    In ancient times, the region in which Dujiangyan now stands suffered from regular floods caused by overflow from the Minjiang River. To help the victims of the flooding, Li Bing, the region governor, together with his son, decided to find a solution. They studied the problem and discovered that the river most often overflowed when winter snow at the top of the nearby Mount Yulei began to melt as the weather warmed.

    The simplest fix was to build a dam, but this would have ruined the Minjiang River. So instead Li designed a series of channels built at different levels along Mount Yulei that would take away the floodwater while leaving the river flowing naturally. Better still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

    Cutting the channels through the hard rock of Mount Yulei was a remarkable accomplishment as it was done long before the invention gunpowder and explosives. Li Bing found another solution. He used a combination of fire and water to heat and cool the rocks until they cracked and could be removed. After eight years of work, the 20-metre-wide canals had been carved through the mountain.

    Once the system was finished, no more floods occurred and the people were able to live peacefully and affluently. Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish populations to exist in harmony.

     The answer to protecting and saving marine(海洋) wildlife can start with cutting back on something Americans use every day—plastic drinking straws. Actor Adrien Grenier, best known for playing Vincent Chase in 2015 movie Entourage, has launched a campaign to reduce the amount of single-use plastic usage in this country in order to protect and save marine wildlife and the environment. Plastic drinking straws are among many single-use plastic products contributing to the shocking loss of marine life, but they're a great place to start because they're something Americans are using by the hundreds of millions without any awareness that they're so damaging.

According to Ecocycle, an international environmental organization, Americans use more than 500 million straws daily, which are enough to fill 127 school buses each day, and they can't be recycled. They means plastic straws end up in landfills or oceans, where fish and other marine wildlife mistake the small bits for food and swallow them. After seeing a photo of a whale beached on the shore with a belly full of plastic, Grenier felt the inspiration to launch the Lonely Whale Foundation, hoping to inspire and educate others on the challenges facing marine life.

     Along with stopping the use of straws, Grenier hopes to educate consumers on the dangers of other single-use plastic items such as grocery bags and water bottles. While many Americans use these plastic products in their daily life, there are more sustainable alternatives that can help protect the environment. Ecocycle recommends the use of straws made from stainless steel, glass, and even bamboo instead of plastic. You can buy a number of these environmentally friendly straws online and in stores.

    A student is learning to speak British English. He wonders: Can I communicate with Americans? Can they understand me? Learners of English often ask: What are the differences between British and American English? How important are these differences?

    Certainly! There are some differences between British and American English. There are a few differences in grammar. For example, speakers of British English say “in hospital” and “Have you a pen?” Americans say “in the hospital!” and “Do you have a pen?”. Pronunciation is sometimes different. Americans usually sound theirs in words like “bird” and “hurt”. Speakers of British English do not sound theirs in these words. There are differences between British and American English in spelling and vocabulary. For example, “color” and “honor” are British, “color” and honor” are American.

    These differences in grammar, pronunciation, spelling and vocabulary are not important, however. For the most part, British and American English are the same language.

    This is my son Matthew's last night at home before college. I know that this is good news. I feel proud that Matthew will go to a great school. I know that this is finest hour. But looking at the suitcases on his bed sends me out of the room to a hidden corner where I can't stop crying.

    Through the sorrow, I feel a rising embarrassment. "Pull yourself together!" I tell myself. There are parents sending their kids off to battle zones. How dare I feel so shocked and upset?

    One of the great gifts of my life has been having my boys, Matthew and Johnowen. Through them, I have explored the mysterious, complicated bond between fathers and sons. As my wife and I raised them, I have discovered the love and loss between my father and me. After my parents' divorce，I spent weekends with my dad in Ohio. By the time Sunday came around, I was unable to enjoy the day's activities because I was already afraid of the goodbye of the evening.

    Now，standing among Matthew's accumulation of possessions, I realize it's me who has become a boy again. All my sadness and longing to hold on to things are back, sweeping over me as they did when I was a child.

    His bed is tidy and spare. It already has the feel of a guest bed. In my mind I replay wrapping him in his favorite blanket. That was our nightly routine until one evening he said," Daddy, I don't think I need a blanket tonight." I think of all the times we lay among the covers reading. I look at the bed and think of all the recent times I was annoyed at how late he was sleeping. I'll never have to worry about that again, I realize.

    For his part, Matthew has been a rock. He is treating his leaving as just another day at the office. And I'm glad. After all, someone's got to be strong. I'm proud that he is charging into the first chapter of his adult life with such confidence.

    Educational APP Store

    Busuu

    Busuu helps you learn English language on the go and the lesson's quality is guaranteed as it is based on CEFR language framework. Lessons range from beginners to advanced learners. Busuu is actually a great English app if you want to improve your spoken English by talking with native speakers.

    Duolingo

    Duolingo is one of the best English language apps today and highly recommended for English beginners. The system of the app helps you learn English quickly by spending twenty minutes a day. Duolingo structures your lessons that teach you about seven new words based on a topic and skill points being awarded for completing the lessons.

    Memrise

    Memrise uses some creative and easy ways to remember English words. The focus of this app is to help the users expand their vocabulary by learning English words in an effective way. Memrise also offers an offline mode to continue learning without Internet connection.

    Rosetta Stone

    Rosetta Stone is designed differently from average language apps on the marketplace today. It's trying to teach us English the way we'd learn it if we were children starting to learn the language, it has exercises designed to help you learn basic words. A variety of lessons are offered that Rosetta Stone has been using for years.

    What is the single most effective way to reduce greenhouse-gas emissions? Go vegetarian (素食)？ Replant the Amazon? Cycle to work? None of the above. The answer is: make air-conditioners better. On one calculation, replacing refrigerants (制冷剂) damaging the atmosphere would reduce total greenhouse gases equaling 90bn tonnes of CO₂ by 2050. Making the units more energy-efficient could double that. By contrast, if half the world's population gave up meat, it would save 66bn tonnes. Replanting two-thirds of tropical forests would save 61 bn tonnes. A one-third increase in global bicycle journeys, just 2.3bn tonnes.

    Air-conditioning is one of the world's great overlooked industries. Automobiles and air-conditioners were invented at roughly the same time, and both have had a huge impact on where people live and Work. Unlike cars, though， air-conditioners have drawn little criticism for their social impact, emissions or energy efficiency. Most hot countries do not have rules to govern their energy use. There is not even a common English word for “coolth” (the opposite of warmth).

    Yet air-conditioning has done more than most things to benefit humankind. Lee Kuan Yew, the first prime minister of Singapore, called it “perhaps one of the signal inventions of history”. It has transformed productivity in the tropics(热带地区)and helped turn southern China into the workshop of the World. In Europe, its spread has pushed down heat-related deaths to 10% since 2003, Men 70,000 people than usual, most of them elderly, died in a heatwave. For children, air-conditioned classrooms are associated with better grades at school.

    Environmentalists who call air-conditioning “a luxury we cannot afford” have half a point, however. In the next ten years, as many air-conditioners will be installed(安装)around the world as were put in between 1902(invention time)and 2005.Unless energy can be produced without carbon emissions, these extra machines will warm the world. At the moment, therefore, air-conditioners create a vicious cycle. The more the Earth warms, the more people need them. But the more there are, the warmer the world will be.

    Cutting the impact of cooling requires three things. First, air-conditioners must become much more efficient. The most energy-efficient models on the market today consume only about one-third as much electricity as average ones, Minimum energy-performance standards need to be raised raised, orintroduced in countries that lack them altogether, to push the average unit's performance closer to the standard of the best.

    Next, manufacturers should stop using damaging refrigerants. One type called hydrofluoro-carbons, is over 1,000 times worse than carbon dioxide when it comes to trapping heat in the atmosphere. An international agreement to knock out these pollutants will come into force in 2019.

    Last, more could be done to design offices, malls and even cities so they do not need as many air-conditioners in the first place. More buildings should be built with overhanging roofs or balconies for shade, or with natural ventilation (自然通风).Simply painting roofs white can help keep temperatures down. Providing indoor air-conditioned comfort need not come at the expense of an overheating world.