摘要
Water is essential to all living organisms.From humans to plants and animals tobacteria,everything on Earth needs water to survive.About 71%of theplanet’s surface area is covered in water,and when seen from space,the Earth looks blue.That iswhy it is called the'blue planet.Approximately 98%of all water on Earth is salt water,which is found in oceans and seas and is home to hundreds of thousands of marinespecies. Only about 2%is fresh water-the water we depend on.We use fresh water for many things.We drink it.
