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    There is a lake near a forest in Sweden. The water in the lake is very clear and everything is quiet and still. On the far side of the water is some farmland and further away, across the field, is an old church built on a hill. It has just stopped raining. The brook(小溪) flowing into the lake is full and there is still some half-melted(半融化的) snow from last winter on the ground.

    The reason the water is so clear, and everything is so quiet and still, is that most of the plant and animal life in and around the lake is dead. There are no birds because all the fish and insects, which the birds need for food, have disappeared. Many trees in the forest are losing their leaves and bark (树皮), and are sick and dying. Others were blown down by the high winds of last winter. A farmer is working in a field planting something, but unless he plants a stronger kind of seed this year, the crop will be between 25 to 40 percent lower than a few years ago. The stones of the old church tower are turning to powder and unless the tower is repaired soon, it will fall down.

    All the death and destruction(破坏) in this place is caused by the smoke coming out of factories and poisonous gases from cars and trucks. And yet this silent lake is hundreds of meters aways from the nearest factory and highway.

    Have you heard about "Face Recognition (刷脸)" technology? It begins to become a popular and exciting development in China. In September 2017, a Kentucky Fried Chicken KPRO restaurant in Hangzhou utilized (利用) this new technology.

    Customers will go through the buffet (自助餐) line and then check out with their food using this "Just look with your face" payment method. When they get to the payment machine, they simply choose the Payment of facial recognition and then stand in front of the screen for 1-2 seconds. They then confirm their account and phone number and finish the payment process—all of it takes no more than 10 seconds!

    Nowadays, the words "Face Recognition" have become popular around China with the development of the ability to pay with facial recognition. Here are several examples of how you might hear the words in daily life in China. In Hangzhou, a high school provides a service where students can pay for meals by facial recognition. However, this isn't the only way we use the words in China! When you combine these characters together you also get another meaning: Jackie Chan got a dinner for free by "brushing his face".

    Do you know more about other meanings of "Face Recognition"? Please tell me more about it by sending an email to Susan2018@126.com or call me at 8524689. We'll talk about the topic next time.

    China Science and Technology Museum was opened to the public in September 1988. But the second project was completed in May, 2000. Its main task is to spread knowledge of science and technology among the public.

    The activities of China Science and Technology Museum include popular science exhibitions, Astro­vision film shows, training education programmes and experiment exhibition programmes. The museum has an area of 40，000 square metres, of which 16, 000 square metres is for exhibition halls.

    The Astro­vision Theatre is one of the museum's major attractions and also one of the largest Astro­vision theatres in the world. It makes visitors feel they are in actual events rather than see a film. Many great science activities are often held at the museum, and the museum wants to be an important window to the world.

    Sitting too much is now listed with smoking and junk food as a bad habit that increases your risk of heart disease.

    New Australian research shows that half-an-hour in the gym will not make up for the waist-expanding damage caused by spending the rest of the day sitting.

    But the good news is that doing chores(家务杂事) in the house or gently walking around the office while on the phone might be enough to keep you fit.

    The study joins the growing body of evidence suggesting too much sitting might undo the benefits of exercise.

    The study measured the intensity(强度)of physical activities in 168 subjects over seven days. If found that, regardless of how much exercise they did or their total sitting time, those who took more breaks from sitting had lower risk of thick waists and lower levels of blood lipids(脂质).

    “Higher levels of blood lipids have been linked to a heightened risk of heart disease,”principal researcher Genevieve Healy of the University of Queensland said. "What the study shows is that there are benefits in just getting up regularly and interrupting your sitting time."

    Researchers behind the Stand up Australia project have written to the Rudd Government requesting $ 3.5 million for a two year study into how long sitting affects the health and productivity of workers.

    The latest study builds on work that is shifting the health promotion focus from purposeful exercise, such as running, to lower intensity activities throughout the day.

    The Australian research bas been backed up US studies, which show standing up is enough to double the metabolic(新陈代谢) rate and the amount of calories burnt.

    “To hold a body that weighs 77kilograms upright take a .fair amount of energy from muscles", said professor Marc Hamilton from the University of Missouri. "There is a large amount of energy associated with standing every day that cannot be easily replaced by, 30 to 60minutes in the gym."

    Trees are useful to man in three important ways: they give him wood and other useful things, they give him cool places, and they help to stop drought and flood.

    Unluckily, in many parts of the world, man has not found that the third of these points is the most important. Man wants to make money from trees, so he has cut them down in large numbers, only to find that without them he has lost the best friends he had. And also, he is usually too careless to plant and look after new trees. So the forests slowly disappear.

    This does not only mean that man will have fewer trees. The results are even worse: for where there are trees, their roots break up soil make the rain in——and also bind the soil, thus stopping it from being washed away easily; but where there are no trees, the rain falls on hard ground and flows away, causing floods and carrying away the rich top-oil. When all the top soil is gone, nothing is left but useless desert.