2 . Thousands of years ago, people didn't live in cold places because they didn't know how to keep themselves warm. Later they learned to make clothes. When an animal was killed, they made use of its skins to cover their bodies. The skins kept them warm. Nature is people's good friend. It once helped people find fire, when lightning(闪电) hit a forest and started a fire. People took some of this fire to their homes. The fire kept them warm, and also frightened wild animals. Soon people found the food cooked tasted much better, so they began to use the fire to cook food. But people still didn't know how to make a fire. When they got a fire from the forest they tried to keep it burning. If it went out, they had to wait for years. But later they found different ways to make fire. For example, they made fire by burning wood or knocking two pieces of stones.

Today it's easy for people to make fire because they have matches, lighters and different kinds of heaters. They can make fire at any time they need.