When you hear about trees cut for paper, you might think of your favorite trees in the backyard, nearby parks or wild forests being cut to pieces.

 The good news is that production and use of paper will not cause forests to disappear. Most trees used for paper come from timberlands(林地). People plant trees here for use. It usually takes 10 to 20 years for trees to grow big enough to be cut down. During that time, trees provide a home for animals and produce oxygen(氧气) for the earth. And after people cut down the big trees, they plant small ones again.

 Often, a tree is not cut down for making paper at all. People use the big part for buildings. Paper is then made from the left small part.

 We also recycle paper—People collect used paper and turn it into new products, likes boxes, newsprint and writing paper, in the factory. So it's important for us to recycle paper and reduce(减少) the amount(数量) of it in landfills(垃圾处理场).

How often do you use your car? Can you use your car less often? Do you know the following facts in the UK?
·About 50% of all car journeys are just for fun.
·Over 80% people go to work by car.
·25% car journeys are under two miles.
·70% car journeys are under five miles.
WALKING & CYCLING

Instead of using the car for short journeys, why not walk or ride a bicycle? Walking is the most popular form of exercise—it's healthy and it can save money. If you work nearby, try walking or cycling instead of driving. Walking your children to school gives them valuable road experience.
BUSES

Bus companies are using new buses: some run on new fuelswhich produce less pollution; some have easier access（通路）for disabled and old people. There are special traffic lanes (行车道)to make bus journeys easier. So do something to help solve the pollution problem—-let the bus take you to work and your children to school.
TRAINS

All car journeys, long or short, can be hard work. For some trips, it is wiser to take the train. Leave your car at home and walk, cycle or take a bus to and from the station. Train travel is fast, safe and comfortable. Train tickets are not always expensive.

    Building an app is a big project. If you want to build the next great smartphone app, you need a plan. First, think about the kind of app that you want to build. Will your app be a game? Will it be for business? Then make a schedule(日程安排)for building the app. You need plenty of time for research before you are ready to build.

    Now you're ready to make the app. Building an app is like a puzzle(拼图)with many different parts. You can build it yourself or find a company to help you. There are many videos and websites that can teach you to build one. Some websites provide "building blocks" for app developers. As you build, you pick blocks from the website and put them in your app.

    After you build your app, you need to check it carefully. Look for bugs. Most apps have several problems to fix. Show your app to people. Ask their opinions. Mike sure everything works before letting people download it. There are so many tools that can help you build apps. Having the right tools will make the work easier. Now almost anyone can make a new app.

    Now, it seems that artficial intelligence （人工智能）is becoming more and more popular in our life, and it has greatly influenced the ways we live, work and play. Can you imagine that you can play table tennis with a robot one day?

    Recently, a scientist has invented a special robot that can be a table tennis coach. That means people can practice table tennis not only with humans but also with a robot.

    Named Forpheus, the smart table tennis robot is quite special. It can study the movements of human players and the speeds of the ball. In this way, it can exactly judge (判断) the player' skill levels (水平). Then it uses the information to change the ways to play. If the player are just beginners, Forpheus will play in a slow and easy way, but if the players are better ones, the robot will play in a faster and more difficult way. What's more, while playing, it encourages players to try their beat with words like "Good job!", "Come on!" and so on. At the same time, it gives some good advice to improve their skills. So it is both a good partner and a clever coach.

    Science and technology is developing quickly these days and it's hard to imagine what will happen in the future. "In the next 20 years, it will be possible that one robot teaches another to play table tennis or even invents another one!" Takuoya, the inventor of the robot, said.

    When your pen is broken, the battery in your toy runs out, or you have some leftover food, what do you do with these things? You will probably throw them all into one trashbin. But actually, all of these pieces of trash need to be sorted (分类) separately.

    Garbage sorting is a big problem worldwide. In recent years, some Chinese cities have been working hard on it.

    Shanghai has worked with Alipay to create a "green account (账户)" service for its residents (居民). Account holders get points by correctly sorting their garbage. Through the Alipay app, they can exchange the points for milk, phone cards and other products. The city is asking all of its residents to sort their garbage into four groups: wet, recyclable (可回收的), harmful and dry.

    Wet waste is also known as household waste. "They are things you don't want but that pigs can eat," Guangzhou Daily explained.

    Paper, metal (金属), glass and other things that can be reused are recyclable waste.

    Harmful waste includes things like medicine, batteries and fluorescent bulbs (荧光灯泡).

    Finally, any waste that's not wet, recyclable or harmful will go in the "dry waste" bin.

    Many other Chinese cities are also using this method to sort their garbage. For example, Shenzhen has been sorting its garbage into the same four groups since 2012. Students there also receive waste-sorting guidebooks that they must study.

    China is improving its waste-sorting efforts. There is still a long way to go. But it's never too late to learn how to sort your trash properly and protect the environment.

    If you don't sort your garbage, all of it will go to a landfill (垃圾填埋场) and be buried together. These landfills can take up large areas of ground that could have been used for planting trees. The electronic waste you throw away, such as batteries, can pollute the soil and water. Other pieces of garbage, like the metal part of a pen, can be used to make other things if they are properly recycled.