【正确答案】topic Based on the lecture, there are two methods to keep the fire burning in ancient days. example 1 The first method ancient human used is from the technical knowledge which people in this stage of the history first found the fire would extinguished little by little without additional wood. They began to use wood as a kind of fuel to keep the fire burning. That is to say, if they kept adding wood, the fire wouldn't die out. example 2 However, fire would easily die out if nobody is watching over. After they realized the the importance of cooperation, they applied this social skill to keep the fire longer. They added wood in turn during the nights and stopped the fire from dying out.

【答案解析】[听力原文] M: As we all know, humankind has been using fire for millions of years. Fire changed the way ancient humans lived. But when ancient human first got in touch with the secret of fire, their knowledge of how to control and manipulate it was primitive. Now let's take a close look at how they kept the fire burning. At a particular stage in human history, ancient human started learning to keep fire with technical knowledge. After lightning stroke a tree, a forest fire began. When ancient humans rushed to put out the flames, they realized that fire can be spreading along with forest trees; otherwise it would gradually burn out without additional wood. Therefore, instead of letting flames flash for few hours before it died out, the ancient human started to apply wood as a kind of fuel to keep the fire on as many hours as necessary. Unfortunately, fire could still burnt out over night if no one watched over it. Therefore, social skill was another approach applied by ancient people to prevent the fire from going out. When everybody slept at night, there was usually a guard looking over the fire and keeping adding wood, and then they took turns through the night. By learning the importance of team work, the ancient people were warm and safe in the cold evenings.