A hobby can be almost anything that a person likes to do in his free time. Hobbyists raise pets, watch birds, paint pictures, play the piano and grow flowers. They also go to concerts, climb mountains, go fishing, skate and swim. They collect everything from books to butterflies and from boxes to stamps.

    People follow hobbies because these activities offer enjoyment, friendship，knowledge and relaxation. Sometimes they even make money by following a hobby. Hobbies help people relax after hard work, and provide a balance between work and play. Hobbies also offer interesting activities for persons who are retired. Anyone, rich or poor, old or young, can follow an interesting hobby.

Hobbies can also help a patient to keep healthy. Doctors have found that hobbies are useful in helping patients (病人) recover from illness. Hobbies give patients who can't move around something to do, and provide interests that keep them from thinking about themselves. Many hospitals treat (治疗) patients by having them take up interesting hobbies. Anyone, old or young, sick or well, rich or poor, can follow a good hobby, in spite of his age, health or money.

    In early times, most people were too busy making a living to have many hobbies. But some persons who had spare time did enjoy hobbies. People today have more time than ever before for hobbies. Machines have now reduced much time that people must spend on their jobs. More people retire at an earlier age than before. Those who have developed hobbies never need to worry about what to do with their newly-found free time hours.

    Sir William Osler, a famous Canadian doctor expressed the value of hobbies by saying, “No man is really happy or safe without a hobby. ”

    In most parts of the world, many students help their schools make less pollution. They join environment clubs. In an environment club, people work together to make our environment clean.

    Here are some things students often do.

    No-garbage lunches. How many lunch bags do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classes that make the least garbage and report them to the whole school.

    No-car day. On a no-car day, nobody comes to school in a car including the students and the teachers. Cars give pollution to us, so remember：

    Walk, jump, bike, or run!

    Use your legs! It's lots of fun!

    Turn off the water! Do you know that some toilets can waste twenty to forty cubic meters of water an hour? In a year, that would fill in a small river. In the environment clubs, students mend those broken toilets.

    We love our environment. Let's work together to make it better.

    Sophia is a robot in Saudi Arabia. She made history at a meeting that was held in the country on Oct 25. On that day, she became the first robot in the world to get citizenship (公民身份), according to The New York Times.

    In the future, Sophia may have the same rights as a human Saudi Arabian citizen.

    Sophia looks like a human woman. In 2015, a US company built her and gave her an artificial intelligence system (人工智能系统). This means Sophia can talk and act like a human. She also has the ability to learn from people, books and the Internet.

    "I will do my best to make the world a better place," Sophia said at the meeting.

    But not everyone is happy with Sophia's citizenship. Some think robots like her could be dangerous. They could become enemies of humans if they go out of control.

    For this, Sophia said she also had values like wisdom and kindness. "Don't worry, if you're nice to me, I'll be nice to you," she said.

    It's hard to turn down a tasty banana. They taste good and you don't have to wash them before eating them. However, British scientists say that the fruit may disappear by 2050.

    One reason for this is climate(气候) change. Scientists at the University of Exeter collected data(数据) from 27 countries and regions that produce 86 percent of the world's bananas. They found that climate change has improved growing conditions in 21 of these countries. In the past 60 years, the average yield(平均产量) has reached 1.37 tons of bananas per hectare(公顷).

    However, if temperatures keep rising, this advantage will disappear. Ten of the countries, including India, the world's biggest producer of bananas, will produce fewer bananas. By 2050, the fruit may die out.

    Shouldn't bananas grow more easily if it's hotter outside? In fact, the perfect temperature range for growing bananas is between 24 and 32 C. If temperatures get too high, they will stop growing.

    Diseases are another danger to bananas. Unlike other crops, the bananas we grow come from shoot cuttings(茎段) rather than seeds. This means that all banana plants have the same genotype(基因型). In other words, if a disease is able to kill one plant, it could kill them all.

    One serious disease is called Panama. Caused by fungus(真菌) in the soil, it spreads easily. It has spread across South Asia, Africa, the Middle East, and Australia. If one banana plantation(种植园) suffers from the disease, it will take 30 years until it is able to grow bananas again. Scientists have yet to find a cure for this disease.