There is a question in the lesson "Understanding Air" on page 9 of the science workbook for the third grade of primary school compiled by Peng Yi Primary School in Xiaoshan District, Du Zhigang Zhejiang Education Publishing House: Can solids be compressed (tick √ or tick ×) in the column of comparing solids, liquids and gases? When some students answered that solids cannot be compressed, they immediately aroused the opposition of other students, and gave examples to prove that sponges are solid, but they can be compressed, and cotton can also be compressed if it is solid. Students use their existing experience and knowledge to prove their views. So can solids be compressed? Is the table here right or wrong? The students are arguing endlessly. The problem of object compression involves the microstructure of the object, which is definitely unclear and unnecessary. Later, I had to use my "authority" to sum up my speech: students dare to express their views, and they can prove that their views are commendable with facts. This is the spirit we need to study science. Regarding whether solids can be compressed, we will get a good solution after learning more scientific knowledge. According to your understanding today, it is right to judge √ and it is also right to judge ×, ok? I don't know if this is correct, please ask your peers to put forward more treatment methods. The following is the information I collected about object compression for reference: Can water be compressed? The simplest answer to this question is that everything can be compressed. In fact, it is much easier to compress gaseous matter than to compress any other form of matter. That's because gas is made up of molecules that are far apart. For example, in ordinary air, the space occupied by actual molecules is about one tenth of the whole volume. When compressing a gas, we only need to overcome the expansion tendency formed by the random movement of molecules themselves, push them closer and squeeze out some gaps between molecules, which can be easily done by human muscle strength. For example, when you squeeze a balloon, you are compressing air. As far as liquids and solids are concerned, the atoms and molecules that make them are only in close contact with each other. As the electrons in the outer region of each atom repel each other, these atoms and molecules are no longer closer together. This means that the compression resistance of liquid and solid molecules is much stronger than that of molecular movement in gas. This means that human muscles can no longer do the work of compressing liquids and solids, at least there is no obvious effect. Suppose you pour a certain amount of water into a rigid container with an opening at the top, and put a closed piston in the opening to make it contact with the water surface. If you press the piston down with all your strength, you will find that it will not move significantly. Because of this, people often say that water is "incompressible" and its volume cannot be compressed smaller. Actually, it's not like this. When you push the piston down, you do compress the water, but the degree of compression cannot be measured. If much greater pressure can be applied than human muscles, the volume of water or any other liquid or solid will be reduced to a measurable level. For example, if you compress 1. 1 ton per square centimeter, its volume will be reduced to 96 liters. With the further increase of pressure, the volume will further decrease. Under this compressive force, it can be said that electrons are getting closer and closer to the nucleus. If the pressure is greater, for example, the pressure is equivalent to the weight of thousands of kilometers of matter accumulated under the great gravity, the electrostatic repulsion will not work at all. Electrons cannot move around the nucleus in orbit, but will be pushed away. Then matter is made up of nuclei without electrons, and electrons fly around in irregular motion. Nuclei are much smaller than atoms, so most of this "degradation substance" is still empty. The pressure in the center of the earth or even Jupiter is not enough to form degraded matter, but there is degraded matter in the center of the sun. A star made entirely of degraded matter can be as heavy as the sun, but it is not bigger than the earth. This is a white dwarf. It can be further compressed under its own gravity until it is composed of neutrons in contact with each other. Such a "neutron star" can have all the mass of the sun, but it is compressed into a sphere with a diameter of more than ten kilometers. Astronomers believe that it can be further compressed until it becomes a "black hole" with zero volume. 2007、4、 10