“What Am I” is taken from the first volume of the second-grade Chinese textbook published by People's Education Press.
This article is a short scientific article that describes changes in water and their advantages and disadvantages in simple, lively language.
In 2017, this article was selected in the new version of the second grade Chinese textbook of People's Education Press. After revision, it became the text of the first group of Lesson 2, and Yang Haibo. saved the text.
Interpretation of the manual
Water is the source of life. Without water, there would be no beautiful and charming world. Water is something that people cannot do without on a daily basis. Clouds, rain, snow, etc. are common natural phenomena that people are accustomed to. We rarely associate water with them and think about their changing scientific laws and principles.
This scientific essayAnthropomorphic uses simple, vivid language to describe changes in water and their benefits and drawbacks. After reading this article, you will unknowingly find yourself in the situation described in the text, and you will seem to have become an ever-changing "water": first, it floats in the sky in the sunlight, and becomes a continuous cloud when it floats; encounters cold condensation, or becomes rain, either hail or snow; when she falls to the ground, she sleeps, walks, runs and dances in the "house" (rivers, lakes and seas).
Water has done many good things and many bad things for humanity. To completely defeat it, we still need to exert strenuous efforts.
What is the reason why human beings cannot live without water? The composition of the second level is as follows:
We cannot livewithout water? live without water in many places. If there was no water in the world, humans would not be able to survive. We must save water. Sometimes one drop of water can save one person's life, sometimes one drop of water can save many people. Water is very useful to human beings. I want to save water, so that our mother nature becomes more and more beautiful.
Don’t waste a drop of water. Even a drop of water will help us a lot. Don't waste water, don't think that water will never run out, water will run out one day. Water is the source of human life. We must take care of nature and save water. Only in this way will our mother nature become more and more beautiful.
The exogenous theory linked to water
As its name suggests, the exogenous theory believes that water on earth comes from exterior of the earth. Water-rich comets and asteroids are candidatespotential to an extraterrestrial water source. Comets known as "dirty snowballs" are composed of water and interstellar dust. When a comet hits the Earth, it brings a large amount of water.
Some water-rich asteroids fall to earth and become meteorites, which also contain a certain amount of water, generally 0.5% to 5%, and some can reach more than 10%, among which Meteorite carbonaceous chondrules contain more water.
Chondrite meteorites are the most common type of meteorite in the solar system, making up about 86% of all meteorites. For this reason, some scientists believe that when extraterrestrial objects such as comets and asteroids strike Earth, they bring frozen water resources to Earth's environment.
However, scientists have discovered that the chemical composition of most comet waterdoes not correspond to that of Earth's water. Furthermore, the above-mentioned scientists from the University of Münster in Germany believe that since the meteorites landed on Earth during the Earth's formation phase, they should leave corresponding chemical traces in the Earth's mantle.
If water had indeed been brought to Earth by meteorites at this point, the isotope levels in the mantle and in the meteorites should be the same, and when they brought the meteorite from the Tagish Lake, British Columbia. A comparative analysis of ruthenium isotopes in the Earth's mantle and ruthenium isotopes in the Earth's mantle found that there was no similarity in the isotopic levels of the two.