Shenzhen's fast development has made it become China's most crowded city!  Here are about 15 million people living on its 1,991 square kilometers. On each square kilometer averagely(平均地) live 7, 500 people. It is 1, 080 more than that in Hong Kong, and nearly 800 more than that in Guangzhou.

    Besides, Shenzhen owns 2 million local vehicles, and about 300, 000 vehicles from other places also run on the local roads every day. The total length of the city's roads is 6, 041 kilometers. It means each resident only owns 0. 58 meters of road!

    As a result, the city is facing serious environment and resource(能源) problem. One of the problems is water shortage. The amount of fresh water for each person of the city is only 25％ of the country's average. What's more, most of the water drunk by Shenzhen people comes from other areas.

    Now, Thailand is popular among more and more tourists from the world, including Chinese. In Thailand we should do the things as Thais (泰国人） do. When we can't do all the things as Thais, we should at least learn and respect(尊重) their customs (风俗). Here's something about their customs.

    Personal appearance (外表) is very important in Thailand as a sign of respect for other people. Your clothes should be tidy, clean and free from holes. Shorts and sleeveless (无袖的) shirts are not welcomed in churches (教堂.) Remember that you will need to take off your shoes when entering rooms, so don't wear shoes that are slow to get on and off. The rules are even stricter(严格) with foreign visitors, so even if you see a local in shorts, it's not OK for everyone.

    It's not polite to touch a Thai on the head, including children. At the same time, don't touch people with your feet, or even point with them because they think feet are dirty and low.

    If someone is sitting with outstretched (伸出的) feet, don't step over them, because this is very rude. It could even make people angry. Even if the person is sleeping, it is best to go around until he or she notices and lets you go out.

    Most schools in England require children to wear a school uniform .

There are at least four advantages. Firstly, when they go on a school trip they all look the same and so they can't get lost. Secondly, it stops kids worrying about what to wear each day. Everyone is equal. Thirdly, parents don't have to shop for expensive and different clothes for their children to show off. Fourthly, wearing a uniform gives a sense of being proud and discipline in them.

    Earlier this year, China achieved a new milestone in space exploration. On Jan 3, Chang'e 4 became the first space probe in history to successfully land on the far side of the moon, People's Daily reported.
    From Earth, we can only see one side of the moon. The other side has been a mystery. Scientists have long wondered what lies on this side of the moon.

    Chang'e 4 has sent back photos of the far side of the moon. It is also being used to carry out experiments, such as growing seeds in a low-gravity environment. The data collected from these experiments could be used to help us build a base on the moon in the future.
    The success of the Chang'e 4 mission is a major achievement for China's space program. It marks a new stage in China's deep space exploration, said Wu Yanhua, deputy head of China National Space Administration.
    China launched its lunar exploration program in 2004, naming it Chang'e. Chinese scientists set three goals—"orbiting, landing and sample returning" – referring to launching probes that could circle around the moon, touch down on its surface and bring lunar materials back to Earth.
    Chang'e 4 has realized the second goal. The third will be achieved during the Chang'e 5 mission , which is set to take place before the end of this year, China Daily reported.
    Following the success of the Chang'e missions, Chinese scientists are looking even farther into our solar system. China's first Mars mission is expected to be carried out by 2020, Wu said.
    In addition to the first-ever soft landing on the far side of the moon, the Chang'e 4 mission has achieved many other firsts. One of them is international cooperation and joint exploration. The experiments will provide valuable data for the scientists.

    Control your house from your hand. Download(下载)a film in just one second. Print a mobile phone at home. These are just a few technologies that we may see this year. Let's take a look at a few of them.

    Smart Screens

    This year, smart screens will be big news. They use AI technology and look like an iPad. Google Home Hub is a good example. It is a smart screen that people can use for everything from looking up video recipes(菜谱)to looking at family photos. You can also connect your other smart devices(设备)to Home Hub through the Internet. You can turn on lights or the TV simply by speaking to Home Hub or touching a button(按钮)on the screen.

    5G Internet

    How fast is your mobile phone network? After 3G and 4G, 5G is on the way. According to Science Daily, it is hoped that the US will test 5G this year, while the UK will do so in 2020. China has already tested 5G in some parts of Beijing and Hebei.

    5G is very fast. Its speed is about 10 to 20 times faster than networks now, the BBC noted. You can download a whole film in just one second with 5G. This used to take a few minutes with 4G networks.

    3DMetal Printing

    3D printing isn't new. It first came out in the 1990s. But it isn't commonly used in everyday l life. 3D printers are expensive, each costing thousands of dollars. In addition, they can only print plastics and other basic materials.

    But now, some 3D printers can print metal. HP can print some small metal parts for cars, such as key rings and gear sticks(操作杆). People can use 3D printing to make things like toys. But what if people could print these at home? This would help save time and money. More people might think about buying their own 3D printers.