Today, nearly five hundred weather stations in sixty countries receive satellite pictures.  When they receive new pictures, the meteorologists compare（比较）them with earlier ones.  Perhaps they may find that the clouds have changed during the last few hours.  This may mean that the weather on the ground may soon change, too.  In their next weather forecast, the meteorologists can say this.
　 So the weather satellites are a great help to the meteorologists.  Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours.  Now they can make good forecasts for three or five days.  Soon, perhaps, they may be able to forecast the weather for a week or more ahead（提前）.

    There are many different kinds of disasters around the world. As an adult you know what to do during a disaster, but what about the children? Some adults think it would probably never happen to them, so they don't teach their children what to do. Before it's too late, here are ways to help you prepare your child for a disaster:

    Educate: It is always good to let your child know about possible disasters. This doesn't mean children have to live in fear. When teaching them about disasters, keep the conversation positive（积极的）by telling them there is a solution（解决办法）to the disaster. Keep the conversations short, allow for questions and answer honestly.

    Prepare: Always be prepared, that is the best advice for children. For example, when preparing for bad weather, get the tools you need, like candles, radios, food, water and medicine. Teach your child what is needed in certain disasters so that they know what is available for them, if ever needed.

    Plan: You should always have a plan for you and your child for any dangerous situation. Write out a simple list that they can read. The plan could start with “listen to an adult's advice and/or call 119”.

    Practice: Once you have got the correct safety tools and worked out the right plan, practice every few months. Practicing what to do during a disaster with your child will help them if the time comes.

    Disasters can't be avoidedbut they can be lessened（减轻）once you areprepared and ready for one.

    In recent years, a number of Chinese technological innovations (科技创新) have been making waves around the world. Among them, four stand out. They are known as "four new great inventions of modern China. They have made our daily lives more convenient.

    High-speed trains

    China created its first high-speed railway line in 2008. Since then, the number of passenger trips has grown by over 30 percent every year. By 2016, more than 5 billion trips had been taken on China's bullet trains(高铁), according to Xinhua News Agency.

    China is currently working on the next-generation bullet trains that will have a top speed of 400 kilometers per hour. By 2020, one-fifth of the country's 150, 000-km railway network will be used by high-speed trains. This network will link more than 80 percent of major cities across China, said Xinhua.

    Mobile payment

    Mobile payment is turning China into a "cashless society" led by the third-party payment companies like Alipay. For example, instead of paying by cash, customers now pay for goods simply by typing a short password into Alipay app on their mobile devices.

    Users can also pay their bills through Alipay, such as their water and electricity bills. Alipay also supports cross-border(跨境的)online and in-store payment, which allows users to buy things on international websites and apps.

    Shared bikes

    Shared bike services started in Western countries. But China has surprised the world with how

quickly it has adopted dockless(无柱的) shared bikes.

    Unlike traditional bike-sharing method, dockless bikes allow users to simply pick up or park a bike on the street through GPS and smartphone app.

    To unlock a bike, you just need to scan a QR code on a shared bike with a smartphone app. After you finish riding, you can park it at available parking areas, lock it and pay for ride through mobile payment services.

    Online shopping

    With around 751 million internet users, China has been the world's largest and fastest-growing line shopping market.

    Online shopping now accounts for 15. 5 percent of total retail sales in China, according to Xinhua. Thanks to lower costs and fewer licensing requirements(执照要求), it's easier for sellers

to open an online shop in China than a brick-and- mortar shop(实体店).

    It also helped to create jobs of rural areas. In 2016, online shopping created more than 20 million jobs in rural areas, with over 8. 1 million running their own online shops, said Xinhua.

    Have you ever had trouble sleeping in a new place? Lots of people do. And now researchers from Brown University in Rhode Island think they know why. They found that one-half of the brain "remains more awake" than the other half when people are trying to sleep in a new place.

    The sleep findings were reported in Current Biology by Brown University. In their report, the researchers said many people report that they have a harder time sleeping the first night at a hotel or other places outside their home. They call it "first-night influence". "In Japan they say, 'If you change your bed, you can't sleep,'" said Yuka Sasaki, one of the report's writers. "You don't sleep very well in a new place. We all know about it."

    The researchers measured brain waves (测量脑波) for 35 volunteers over two nights in a laboratory. The two nights were a week apart(间隔).They found during the first night the left half of the brain was more active than the right half. This was during the first deep-sleep period, the researchers said.

    Sasaki said a lot of questions remain.

    Researchers did not keep measuring brain waves all night long. So, they don't know if the left half keeps "watch" all night, or whether it" works in shifts (轮换) with the right half later in the night" .They also do not know why the brain activity, at least during the first period of deep sleep, is always on the left half.

    For some, this research may be calming. It is good to know that our brain is "looking out for us" in a new place. But it may not help with sleep. That brain activity, at least according to this new research, makes it harder to get the sleep people need to wake up well rested in the morning.