Man discovered fire many thousands years ago. The first time he saw was probably when a tree was struck by lightning. He soon learned how to make fire for himself. However, man probably made his fire by rubbing two sticks together.

Fire was very important to man. He needed fire to keep himself warm at night. He used fire to cook his food. He used fire to frighten away enemies and wild animals. In some parts of the world he used fire to signal messages. Red Indians, for example, used fire to make smoke signals. In some other countries people lit fires to warn thier friends of danger.

Fire was very also used to give light. Before the invention of oil lamp, men used burning sticks as torches. And before man discovered gas and electricity, he hung small fires in wire baskets from posts to light the streets.

One man even used fire to tell the time. He invented a candle clock. He made a candle that took exactly twelve hours to burn. Then he marked this candle in twelve equal parts. He lit the candle and could tell the time by counting the number of parts of the burning candle. But the candle clock did not always work well. If there was a wind blowing on the candle, the flame burned too quickly.

A. from a tree stuck by lighting

B. by rubbing two sticks together

Thông tin: However, man probably made his fire by rubbing two sticks together.\

Chọn B