Wang Xuanbo, Class Two, Grade Five, Jiefang Street Primary School
One of the popular science knowledge-the harm and benefit of dust
Dust is the enemy of human health, so people especially hate it, because it carries many bacteria, viruses and eggs everywhere and spreads diseases. Industrial dust and fiber dust can make workers suffer from various incurable occupational diseases. Excessive dust will also cause environmental pollution, affect people's normal life and work, and induce human respiratory diseases.
However, the contribution of dust can never be erased. If there is no dust in the atmosphere, sunlight will not be absorbed, reflected, scattered and refracted, and the sky will be either too bright or too dark. Because dust is a hygroscopic particle, without its core, water vapor in the air can't condense and clouds in the sky can't form. Without the cover of clouds, the surface will become dry and barren, and the weather will be either too hot or too cold. Without dust, many harmful rays in the universe will break into the earth's surface without hindrance, posing a fatal threat to human beings and all kinds of creatures.
Although Dust has many shortcomings, its contribution is endless. It can make the earth get solar energy gently, and it can also make enough condensation nuclei in the atmosphere, increasing the chances of cloud and rain formation. Adjust the surface temperature to make it suitable for the survival and reproduction of life.
The role of dust tells us that everything has its two sides, even some things that people regard as "waste" often have its existence value that cannot be ignored. Only by correctly understanding them can we seek advantages and avoid disadvantages and benefit mankind.
One of popular science knowledge-daily knowledge
1. During the day, birds shuttle between branches and fly freely under the blue sky. At night, they should rest, sleep and recover their strength like us, but they sleep in different postures.
2. sorbet bubbles because there is a lot of invisible water vapor in the outside air. When it meets a very cold sorbet, it will liquefy into droplets and surround it when it is cold. It seems that the sorbet is bubbling.
Sunflower stems contain a wonderful auxin. This auxin is very afraid of light. When receiving light, it will go to the backlight side, and at the same time, it will stimulate the cells on the wide side of the back to multiply rapidly. Therefore, the backlight surface will grow faster than the smooth surface, causing the sunflower to bend to the optical rotation.
4. The shell (exoskeleton) of cicada is hard and can't expand with the growth of cicada. When the cicada grows to a certain stage, the cicada's exoskeleton restricts its growth, and the cicada loses its original exoskeleton, which is cicada slough.
5. Bees spit the sweet juice from the collected flowers into the empty hive, and at night, they suck the sweet juice into their honey stomachs for modulation, and then spit it out and swallow it, so it takes 65,438+000 ~ 240 times to brew the sweetness.
Popular science knowledge-popular science riddle;
Get to the bottom of it (name a popular science work in China)-100,000 Why?
Midnight (cite a modern literary work of China)
New Year's greetings (with a short story by Lu Xun as the title)
They are tall again in the weeds of the spring breeze (the name of Lu Xun's works).
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