On Dec. 9, 2021, three Chinese astronauts gave a science lesson 400 kilometers above Earth! Zhai Zhigang, Wang Yaping and Ye Guangfu, who are working aboard the Tiangong space station, showed millions of students their life there. They also did some fun science experiments（实验）. Let’s take a look at some of them.

Use it or lose it

The human body grows with the pull of Earth’s gravity （重力）. But in space, our bones（骨头）and muscles（肌肉） don’t need to support our body’s weight. This will cause bone and muscle loss. Astronauts can lose up to 20 percent of their muscles after just a couple of weeks. That is dangerous for astronauts because they will be too weak to work.

Astronauts have different ways to prevent（阻止） this. They can wear a special uniform called a “penguin suit”. There are many elastic bands（弹力带） inside the suit. Wearing it astronauts use their muscles to pull the bands to keep their muscles strong. They can also walk on a treadmill（跑步机） and ride a bicycle. Astronauts exercise with these tools every day to prevent muscle loss.

Space water is different

During another experiment, Wang made a water film（膜）. Then she added more water drops onto the film to make it a water ball. This can never happen on Earth. Why? It’s because of the surface tension （表面张力） of water, which is like a “skin” of water. One example on Earth is that some bugs can “walk on water”. Most of the time, gravity is too strong and it breaks the “skin”. But with zero gravity in space, the “skin” stays strong and the water ball will not break.

Maybe you are an average （普通的） student. You probably think you will never be a top student. This is not necessarily so, however. Anyone can become a better scholar（学者） if he or she wants to. Here’s how:

Plan your time carefully. When you plan your work, you should make a list of things that you have to do. After making the list, you should make a schedule （日程表） of your time. First your time for eating, sleeping, dressing, etc.     21     Don’t forget to set aside enough time for entertainment. A weekly schedule may not solve all your problems, but it will make you realize what is happening to your time.

Find a good place to study.     22     Keep this space, which may be a desk or simply a corner of your room, free of everything but study materials. No games, radios, or television!

When you sit down to study, focus on the subject.

Make good use of your time in class. Take advantage（优势） of class time to listen to everything the teacher says.     23     Taking notes will help you remember what the teacher says.

Study regularly. When you get home from school, go over your notes. Review the important points that your teacher mentioned in class. If you know what your teacher is going to discuss the next day, read that material.     24     If you do these things regularly, the material will become more meaningful, and you will remember it longer.

    25     The purpose of a test is to show what you have learned about a subject. They help you remember your new knowledge. The world won’t end if you don’t pass a test, so don’t be overly worried.

There are other methods that might help you with your studying. You will probably discover many others after you have tried these.

We don’t know when Chinese people started to _______ Mid-Autumn Festival. There are many _______ folk stories about this festival. But the most touching one is the story of Chang’e. She was Hou Yi’s _______. Hou Yi shot down the nine suns and _______ the people on the earth. A goddess was so thankful that she gave Hou Yi a kind of magic _______. Whoever drank the medicine could live forever. Hou Yi _______ to drink it with his wife. But Feng Meng tried to steal the medicine. Chang’e refused to give it to him and drank it all. As a result, she became _______ and flew up to the moon. Hou Yi was so sad that he _______ her name every night and wished his wife could come back. One night, he found the moon was so _______ and round that he could see his wife there. Then he quickly laid out her favorite fruits and desserts in the garden.

From then on, people started the tradition of eating ________ and admiring the moon on Mid-Autumn Festival.