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    Artificial intelligence（人工智能）, or AI in short, is the science of giving computers and machines ability to think and work like humans. AI scientists and engineers have made a lot of cool technologies.

    AI is rapidly catching up with the human ability to read faces. As a result, facial recognition（识别）is used a lot in the world. Chinese police use this technology to identify criminals（罪犯）.Once they caught a criminal when he attended a concert. It also checks the ID of ride-hailing（网约车）drivers and lets people pay for things with a smile.

    AI is also used in self-driving cars, which are believed to be the future of driving. Most drivers may wave or nod at passers-by to let them cross the street, but self-driving cars don't have this ability. Carmakers are testing a light signal system to help them "speak" to humans. The system can show what self-driving cars will do. For example, if a driverless car is yielding（让路）, it will flash two white lights side to side. A rapidly flashing light tells passers-by that the car is about to speed up.

    Service Robots also show you know powerful AI is. Imagine this—you come back home from school and your robot housekeeper is waiting for you at the door. After dinner, he teaches you to play the piano, just like a real music teacher. Such thoughts will soon happen in the real world. In the future, more and more service robots will become good home helpers.

    AI is so powerful that it can help human beings and even replace us in many jobs.

    Solar storms shake Earth's magnetic field(磁场). They not only influence human technology, but also animals, reported Forbes.

    Studies show that many animals use changes in Earth's magnetic field to find directions. These changes provide the animals a general compass(指南针) for south and north. Animals can also use them as landmarks.

    For example, scientists have found special cells in part of a bird's eye nervous system(神经系统). They seem to react to changes in the magnetic field.

    Some fish species, like the common trout，have cells with magnetic sensors in their nasal cavity(鼻腔). In 1994 "magnetic sense" was also discovered in sea turtles.

    Some whale species may use magnetic sense to navigate (导航) the oceans. A dysfunction of this sense may explain the still mysterious beachings (动物搁浅). Sometimes several hundred animals, such as whales and dolphins, are driven out of water along beaches. They usually can't breathe under their own weight and die slowly.

    When people think of tigers, words like" strong" and " dangerous" come into their mind. But now, the big animal is calling for our help. There were once eight kinds of tigers in the world, but three died out during last century. In the past 70 years, the number of Siberian tigers has gone from as many as 300 to somewhere between 18 and 22.

   World Wildlife Fund started a programme. It is about to put an end to tiger poaching(非法狩猎) and save wild tigers. China, together with 12 other countries, has joined in. The aim is to double the number of wild tigers in the next ten years.

According to the research by Chinese officers and WWF, the Siberian tiger is already one of the planet's most endangered animals. "If the government doesn't do anything, it's quite possible that there will be no more Siberian tigers in China in 10 to 20 years." said Zhu Chunquan, director at WWF Beijing office.

    Wild animals such as deer and wild bears are tigers' main food. The poaching of these animals is the greatest danger to tigers. Another one is the trap(陷阱). "Volunteers from WWF remove traps every year, but we cannot clear all the traps ourselves," Zhu said. The most important thing people can do is to save the animals tigers eat." To protect the tigers, we need to call on more people to stop hunting wild animals."

In San Francisco, there is a special group of volunteers. They call themselves Friends of the Urban (城市的) Forest (FUF). These volunteers want to {#blank#}1{#/blank#}. Every year, the FUF plants nearly 1,000 trees.

The FUF welcomes new volunteers all year round and in all parts of its work. On Weekend Planting Days, FUF volunteers work with common citizens (市民) to plant trees. The planting usually runs from 9 a.m. to 1 p.m. After the work is done, everyone {#blank#}2{#/blank#} over a community lunch.

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Early to bed and early to rise makes a man healthy, wealthy (富有) and wise (聪明). This is an old English saying. It means that we should go to bed early at night and get up early in the morning. If we do, we shall be healthy. We shall also be rich and clever.

Is this true? Perhaps it is. The body must have enough sleep. Children of your age need ten hours' sleep every night. If you go to bed late, you can't have enough sleep. Then you can't think carefully and your homework will be wrong. You will not be wise and you may not become wealthy!

Some people go to bed late at night and get up late in the morning. This is not good for them. We should sleep at night when it is dark. The dark helps us sleep well. When the daylight comes, we should get up. This is the time for exercise. If the body is not used, it will become weak.

Exercise keeps it strong. Exercise helps the blood (血液) to move around inside the body. Blood takes nutrition (营养) to all parts of our bodies. The brains (大脑) in our heads also need blood. We think with our brains. If we keep our bodies healthy, and take exercise, we can think better!

Our bodies also need air to breathe (呼吸). Without air we will die. Get up early in the morning and we can have plenty of clean, fresh air. That will keep us healthy and happy.