根据短文内容，回答问题 Many years ago, people use a stick, a large piece of wood and dry leaves to make a fire. Today, wood, gas (煤气) and electricity (电) can all make a fire. I think wood is the most dangerous. And I like gas most because it's easy.
People use fire in many ways. At home, people use fire to cook food and boil water. In factories, workers use fire to melt (熔化) metals (金属) to makes things of different shapes. Some workers use fire to make glass.
Fire can help us to do many things, but sometimes fire is dangerous. Cigarettes and campfires can all start a fire in the countryside, in schools and at homes. We must be careful. We mustn't smoke in the countryside, and we mustn't cook without an adult (成年人). We mustn't play with matches. We mustn't play around a fire.
