Water is very important for living things. Without water, there can be no life on Earth. All the animals and plants need water. Man also needs water. Water is found almost everywhere. Even in the driest part of the world there is some water in the air. As we all have found out, water may be solid, liquid or gas. When it is solid, it may be as hard as brick. When it is liquid, you can pour it out of a container. When it is gas, you cannot see or feel it. Although about 70 percent of the Earth's surface is covered with water, there are many places in the world still running out of water. So we should make good use of water on Earth.