Air is a mixture of gases, but when a person exhales air, it contains a large amount of oxygen. And when you exhale, air is already processed by the lungs with a large amount of carbon dioxide. In other words: when inhaling, the air is enriched with oxygen, and when exhaling, the amount of oxygen is very small, but the amount of carbon dioxide increases.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.