There is no water in the world that can never run out
Water is one of the most precious resources on earth and an important foundation for human survival and development. However, the Earth's water resources are limited and unevenly distributed, and many regions are facing severe water scarcity. However, there is one type of water that can never be used up, and that is "tears".
Tears are an emotional expression in the human body, and when people feel negative emotions such as sadness, pain, anger, etc., tears are shed. Tears are secreted by the lacrimal glands in the eye and contain some salts and proteins, but do not contain anything that can be used. Therefore, while tears may seem like a resource, in reality it cannot be used by humans.
In addition to tears, there are other water resources that cannot be used by humans. For example, although seawater is abundant, it is too salty to be used directly for agricultural irrigation and industrial production. In addition, some polluted water resources are also unusable by humans because they contain harmful substances.
Therefore, although the water resources on the planet seem to be endless, the freshwater resources that can be used by humans are actually very limited. We should cherish every drop of water, save water, and protect water resources to ensure the survival and development of mankind.