Wind power is a very clean source of energy. This is how wind power works. Wind makes windmills spin (旋转). When the windmills spin, they make electricity. Then we can use the electricity.

    A lot of people think that wind power is new, but that's not true.

    For thousands of years, people have used wind to sail boats and move water. We still do those things today, but these days we mostly use wind power to make electricity.windmills

    Wind power is a very popular source of energy. Most people think that we should use it more and more. First of all, it's clean. Windmills don't pollute the environment at all. Second, we can use wind power forever. After all, we will always have wind. Also, wind power is cheap, and it's getting even cheaper.

    A lot of people don't understand wind power very well. They believe that there are problems with wind power, but many of those problems are not real. For example, some people say that windmills are dangerous for birds. They used to be true, but it isn't true anymore. Old windmills killed birds because they spun very fast. New windmills spin slowly, and they aren't dangerous for birds.

    However, there are real problems with windmills. One problem is that many people think windmills are very ugly. This is a problem for people, because windmills are often in very pretty areas. Also, wind doesn't blow all the time, so we can't use wind power all the time. Finally, windmills are noisy.

    Wind power is becoming more and more common. Right now, more than 80 countries use wind power. About 2.5 percent of the world's power comes from the wind. For some countries, that number is a lot higher. Wind power gives Denmark more than 25 percent of its electricity.

    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.

    People and dogs have been living together for hundreds of years. When did dogs and people become friends? Where did dogs come from?

    A group of scientists tried to answer these questions. They just finished a study about the history of dogs. In the study, they looked at the DNA of dogs all over the world and found that dogs, like humans, shared DNA with their family members. The scientists put together a big family tree for dogs. It went all the way back to the animal's beginning.

    In this way, scientists learned about the history of dogs. The first dogs lived in Asia. They were born about 33,000 years ago. At first, there were only about 6,400 of them. Their parents were wolves(狼).

    The new study answers many questions. It raises some too. For example, what caused wolves in Asia to become dogs all those years ago?

    One idea is that their DNA slowly changed and the wolves became dogs in the end. As time goes by, dogs became "man's best friends" Or it could happen the other way around. It was possible that some wolves started living with people before they became dogs. Living with people led to many changes to these wolves. It changed their DNA, so their offspring(后代) became dogs. In other words, it was possible that wolves were our friends before they became dogs.

    By studying DNA, scientists now have a much better understanding of the history of dogs. ________.

    How exactly dogs came to be our friends is still unclear.

Live- streaming(直播) has become very popular in China. Viewers( people who watch it) can communicate with hosts by sending them messages, buying them gifts, or tipping( giving them some money). 

 However, some children are spending too much money on live- stream platforms(平台). Earlier this year, a 17- year old boy in Hubei, sent 150, 000 yu an to a host. That was his parents' life money. 

 To stop things like this from happening again, the National Radio and Television Administration introduced a new rule on Nov 23 to better manage(管理) live- streaming services. 

 The rule bans children from giving money or sending gifts to live- stream hosts and performers. It also asks people to register(注册) on live- streaming sites with their real names. 

 Parents welcome this new rule very much. According to China Daily, about one- fifth of live- stream viewers in 2021were children. 

" Online shows and live- streaming have become so popular. I always feel worried that my son might become lost in them. " said a mother of a 15- year- old boy in Beijing. " Stricter rule makes me feel safer. "

In addition, there are some other ways to help manage live- streaming services. For example, live- streaming platforms will put a limit(限制) on how much money people can send to the hosts. When viewers reach the limit, they will not be able to send gifts or give money. If the host asks viewers to send gifts or tips, he or she will be added to blacklist(黑名单). 

Hi! Do you know who I am? Well, my name is Lost and Found. I am a box. Now I am in Classroom 2E, No.1 Middle School. You can see a pen, a watch and a notebook in me.

Your teacher asks you to collect your classmates' opinions about their favorite school lunches. After asking everyone, you have collected a lot of data(数据) or information and aren't sure how to organize it. Creating a graph (图表) can be a great way to organize and share your data.

Graphs show data in a direct way that is easy to read and understand. There are many different kinds of graphs. Different graphs are better for different kinds of data. Read on to find out about the types of graphs in math, as well as the key parts of a graph.

Bar chart

A bar chart has a horizontal axis (横轴) and a vertical axis(竖轴). It has a title that explains what it shows, and different bars are used to show different amounts. There's a number line along the vertical axis and labels(标签) along the horizontal axis, labeling the data.

Pie chart

A pie chart helps organize and show data as a percentage of a whole. True to the name, it looks a bit like a pie and uses a circle to show the whole. Pieces of that circle, or "pie", stand for the different things. The different pieces of the pie are different sizes depending on how much of the whole pie they show. Each piece is labeled to show what it means.

Line graph

Line graphs are used to show changes to numbers over time. They show what we call continuous data. The vertical axis explains the data being shown. We mark data on a line graph. The different data points are then joined up with straight lines, so we can look at the trend(趋势) it shows.

Flow chart

A flow chart shows the different steps in something using boxes and arrows(箭头). It can often have many different directions and different paths you can take using the information it asks for. Flow charts can be great for explaining a huge process by breaking it down into different steps.