1、题目关键词：points and examples, explain

 2、答题要领：

 (1)summarize the two possible ways.

 (2)use examples to explain each one.

 3、听力材料要点：

 (1)The use of primitive campfires: when humans take the stones and cover the fire partially to keep the fire confined, the fire melts the copper that some stones may contain.  

 (2)Pottery. People used colored stones to decorate potteries and one type of stone contains copper. The hot temperature in the oven releases the copper from other ingredients.

 4、模板

 (1)In the listening material, the professor discusses two possible ways early humans discovered how to use fire to release copper from solid rock.

 (2)The first one is ...

 (3)The second one is ...