If you look at the top of your phone, you'll usually see a lite symbol that says 3G or 4G. The "G" is the generation(代)" of your mobile network (移动网络). But these symbols will become things of the past after 5G networks fully arrive.

    On March 30, 2019, Shanghai vice mayor (副市长) Wu Qing made the first SG video call on a Huawei Mate x smartphone, CGTN reported. Shanghai has also become the first city in China to start testing 5G networks.

    About 100 times faster than 4G networks, 5G will let people download (下载) and upload data (数据) faster than ever before. But 5G won't just bring faster mobile internet. People can use it for many other things as well.

    For example, 5G will help to make self-driving cars safer. Today's self-driving test cars have one problem-lag (延迟). When the car "sees" an obstacle (障碍物), it sends this information to a data center and receives instructions (指令).

    However, it takes time to send and receive this information. With this kind of lag, the cars might hit each other because they don't receive instructions in time. With 5G, this lag will be greatly lowered (降低), making the cars safer, according to CNN. 5G could also be used to help the internet of things (IoT,物联网). IoT is a large online network that connects all things and people. Fast internet speed will be the key to developing this technology. The IoT could be used in a lot of ways. For example, with IoT, your refrigerator could automatically (自动地) place an order online for eggs when it finds that there are no eggs left inside.

    Have you noticed your life becoming a little easier? Now, when you go to a certain shopping mall, you can enjoy its free Wi-Fi there. When you want to take a taxi, you can book one with your phone. In fact, all these can be seen as the basic parts of a smart city.

    The idea of a smart city was brought up by US company IBM in 2010. Generally, a smart city is a city that uses digital technologies such as the Internet to improve city planning, save money and resources, and make our life convenient. How smart can a city be? Here are great examples that we can learn from.

    In 2009, Dubuque became the first smart city in the US. The city used smart water meters to take the place of traditional water me tens. They can detect (探测) water waste and leakage (泄漏) and send data to let the house owner know. The same system is used for other city resources like electricity and natural gas. In this way, people know how they use their resources and are glad to help reduce waste.

    Santander in Spain also gives us a look at the future. If people point a phone toward a nearby bus stop, the phone immediately shows all bus lines that serve the stop as well as their arrival times. The government organized a research team and provided an App (应用程序) that collects data on almost everything: light, temperature, and the movements of cars and people. Opening the App near a supermarket provides immediate information on special offers.

    China's first artificial intelligence (AI) textbook series designed for primary and secondary school students is expected to be introduced into hundreds of campuses across the country in 2019. The textbooks will be used for elective courses or as part of school﹣based curriculums.

    Significant progress is being reported in China in AI technological research and development, with authorities now moving to promote AI﹣related education.

    According to the publisher, East China Normal University Press, the series will have 10 volumes, with six volumes published so far. Each has its own theme, with 12 to 14 main chapters and 2 to 4 chapters of activities. This series covers the educational demands of students from primary school to high school on AI and provides a systematic framework of AI knowledge.

    The books have been used in three schools in Shanghai as a pilot program and well received by students, according to Wang Jiqing, chief editor of the series.

    Imagine one day, the water taps (水龙头) in your house stop running. You have to buy water from shops. And still there isn't enough for everyone. Your mother has to save the family's shower water to do other things. Would you be able to stand that kind of life?

    Probably not. But that's what kids in Yemen are experiencing. Experts said Yemen is going to be the first country in the world to run out of water. According to a report, the capital, Sana, will run out of drinking water as early as 2025.

    Because of the shortage, the government often cuts the water supply(供应). Hannan, an 18-year-old from Lahej, told Times, "In a good week we'll have a water supply all week. But then the following week there will be water only for a day or two."

    Hannan said only rich people have enough water to use. They can buy water from the shops or from the water trucks. Private companies own the trucks. They travel around the city every day to sell water—at very high prices. "A lot of people can't afford it," she said.

    The average(平均) person in Yemen uses 100 to 200 cubic(立方) meters of water per year. That is far below the international water poverty(贫困) line of 1,000 cubic meters.

    The government is thinking of making use of seawater. But it will cost a lot and it may not happen soon enough to help the people of Yemen.

    Bruce collected the papers Clive collected the cans

    And Mort tied them with string And Dean washed them all clean

    Jason helped Bruce carry the papers Ruby helped Clive carry the cans

    All the way to the recycling(回收) bins All the way to the recycling bins

    When we recycle, we help the plants

    We help the creatures, from eagles to ants

    We help make the world a healthier place

    For one and for all in the human(人类) race

    Would you like to go to the zoo at night? Last month, Shanghai Wild Animal Park opened its night safari(夜间观赏)for the first time. You can see animals in the dark. Some animals enjoy the night—they are nocturnal(夜行的)animals. Who are they?