题型:阅读选择 题类: 难易度:普通
江西省九江市永修县第三中学2024-2025学年八年级上学期阶段二质量检测英语试卷
How do astronauts stop bone and muscle (肌肉) lose? Do water fly away when astronauts have a drink? On Dec 9, Chinese astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu gave a lesson on Tiangong Space Station. They did some science experiments (实验). Lots of students watched it and learned many amazing science facts.
Use it or lose it
The human body grows with the pull of Earth's gravity (重力). But in space, our bones and muscles don't need to support our body's weight. This will make bone and muscle lose. It is dangerous for them.
Astronauts have different ways to solve the problem. For example, Ye Guangfu was wearing a special uniform. There are many elastic bands (弹力带) inside it. Astronauts use their muscles to stretch (拉伸) the bands. This keeps their muscles strong.
Wang Yaping also showed students how she walked on a treadmill (跑步机) and rode a bicycle. Astronauts exercise with these tools every day to stop muscle loss.
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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 the earth. Why?
We need to first understand the surface tension (表面张力) of water. Surface tension is like a"skin" (皮肤) of water. The "skin" is there because water molecules (分子) are drawn to each other. On the earth, gravity is too strong and it breaks the "skin". But with zero gravity in space, the "skin" stays strong and the water ball won't break.
Space water is different in many other ways from that on the earth. For example, water won't fall down if you pour it into a cup. That's why astronauts usually drink water through straws (吸管). If astronauts cry, the tears won't fall down. They'll stay on their eyeballs.
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