听力原文： Many thousands of years ago, people lived only in hot countries. They did not live in cold countries because they could not keep warm. At first men did not know how to make a fire. Sometimes lightning hit a forest and started a fire. The people took some of this fire to make a fire near their homes. A fire was very important for three reasons. It kept them warm. It frightened wild animals, because they did not attack when they saw a fire. And then another thing was discovered: if you cook food, it tastes much better! Men still did not know how to make a fire. When they had a fire they did not let it stop burning. If it went out, they could not start it again. They had to wait for lightning to start another fire! Sometimes they had to wait for years. Later they discovered how to make a fire. If you rub pieces of wood together, they become hot and burn. You have to rub very fast! One way of doing it is to make a little hole in a piece of wood. Pieces of wood or dry leaves are put into the hole. Then you put the end of a stick into the hole. You rub the stick between your hands. This makes it turn very quickly. The end in the hole becomes very hot. The small pieces of wood and dry leaves begin to burn. Another way of making a fire is to knock two stones together. This makes a spark. You can use this spark to start a fire. Nowadays we have matches. We can carry them in our pockets and make a fire when we want to. We also have cigarette lighters. They are, perhaps, handier and more useful than matches. There are, of course, other advanced methods of making a fire. Many people use heaters to keep warm. Oil heaters bum oil. Gas heaters burn gas. Electric heaters use electricity. We also use oil, gas and electricity for cooking. How was fire first made?