Water (h? O) It is an inorganic substance composed of hydrogen and oxygen, and it is a colorless and odorless transparent liquid at normal temperature and pressure.

Water is one of the most common substances, an important resource for all life, including human beings, and the most important component of organisms.

Water plays an important role in the evolution of life.

People's understanding of aquatic products has a long history. In China's ancient and western simple material views, water was regarded as the basic component, and water was one of the five elements in ancient China. There was also water in the four-element theory of ancient western countries.