A new rubbish sorting system (垃圾分类系统) has been put into use in Fangchengyuan Community in Beijing. Local people not only sort their rubbish, but also put QR codes (二维码) on it.

    "When the rubbish is collected and the codes are seen, I will get reward points to exchange for small gifts and even some money," one of the local people told reporters. "It's really creative and encouraging."

    This smart system has been carried out in 350 communities in Beijing. The capital of China has joined a list of cities in the country that take action to support rubbish sorting. For example, Shenzhen and Shanghai have made laws to punish people and organizations for not sorting rubbish correctly.

    China produces quite a lot of rubbish every year. Much of the rubbish is buried (填埋) in soil or burned without being sorted. Landfills (填埋场) take up a lot of land and have a risk of polluting the soil and water nearby. And burning rubbish can produce harmful gases. Through rubbish sorting, we can reduce the use of landfills and air pollution.

    What's more, rubbish sorting saves resources, which could bring economic benefits (经济利益). For example, a ton of waste paper can be reused to make about 850 kg of paper, saving 17 trees and 50 percent of water. Because of the benefits, some countries have developed successful sorting systems.

    Japan has a strict and detailed system. When people throw away a water bottle, the cap, the wrapper (包装纸) and the bottle itself have to go into three different bins. Every year, families receive special rubbish sorting timetables and directions from their local governments. They are advised to follow the timetables and directions when they throw away rubbish.

    In Australia, every family is provided with three rubbish bins—the red lid (盖子) bin for "general waste" like food and plastic bags, the yellow lid bin for "recycling" like steel and glass, and the green lid bin for "green waste" such as grass and leaves. On the streets, the bins are printed with pictures of the things that are allowed inside. It makes recycling quite easy.

One afternoon, I went to pick up my mother from work. I got there a little early, so I stopped my car by a small park and waited for her in the car. 

As I looked outside the car window, I saw a little boy, around two years old, running freely on the grass as his mother watched him from a short distance. The boy had a big smile on his face as if he had just been set free after being indoors for too long. He would then fall to the grass, get up, without even looking back at his mother, run as fast as he could, again, still with a smile on his face, as if nothing had happened. 

At that moment, I thought to myself "Why aren't adults this way? "Most adults, when they fall down, make a deal of it and don't even make a second attempt (尝试). They would be so embarrassed that they would not ty again if someone saw them fall. Or, because they fall, they would find a good excuse for themselves that they are not fit for it. They would end up too afraid to attempt again for fear of failure. 

However, with kids, when they fall down, they don't consider their falling as a failure. Instead, they treat it as a learning experience. They try again and again until they succeed. The answer must be that they have not connected "falling down" with the word "failure". As a result, they are not discouraged in any way. Besides, they probably think to themselves that it is quite okay to fall down and it is not wrong to do so. In other words, they allow themselves to make mistakes, so they remain energeti C. 

I was deeply impressed by the boy's persistence and the manner in which he did. 

Do you know citywalk? Many young people like it very much in China now. They think it's 1 .

When young people arrive 2 a new city (城市)—Beijing, Shanghai and Chengdu, they like to 3 with good friends around the city. For them, citywalk is "walking around the new 4 " on foot.

Citywalk helps young people to 5 a city. People usually follow a city route (路). When they walk, they can learn the local culture (当地文化) and have 6 food. It also helps them make 7 new friends.

Citywalk follows one 8 : don't go to the center places. 9 these places are busy and 10 . People can not feel free there.

Scientists have found that plants can make sounds. 

A scientist, Lily Hadany, and her team recorded(录制) tomato plants at different times. It showed that the plants made ultrasonic(超声波) sounds. People could only hear them with the help of a computer. They were noises like clicking(发出咔嗒声) sounds. 

As scientists studied the sounds, they began to find some interesting facts. Plants made different sounds at different time. They seldom clicked when they had enough water, but when they needed water, they clicked more and more. Scientists also found that plants made sounds when they got hurt. When scientists cut off a leaf from the plants, the plants also clicked more. But this kind of clicking wasn't the same as when the plants needed water. 

Some scientists designed a computer AI system to tell the different kinds of clicking sounds. It was able to find the difference between plants that needed water and plants with cuts. It means that one day we may be able to use these sounds to figure out when it is in difficult time, and what problem it is having. That could be very helpful to farmers. 

The team's finding changes our ideas about plants. As Dr Hadany says, "Even in a quiet field, there are sounds made by plants, and those sounds carry information and may help us a lot. "

The summer holiday is coming. Here are four fun courses for you.