A：Welcome to the Zhoukoudian caves here in China. It is 61._____ great pleasure to meet you students from England，who are interested in archaeology. You must be aware that it’s here 62._____ we found evidence of some of the earliest people who lived in this part of the world. We’ve been excavating here for many years and... S1：I’m sorry 63._____ (interrupt) you but how could they live here? There are only rocks and trees. A：Good questions. You are an acute 64._____(observe).We have found human and animal bones in those caves higher up the hill as well as tools and other objects. So we think it is 65._____ (reason) to assume they lived in these caves，regardless of the cold. S2：How did they keep warm? They couldn’t have mats，blankets or quilts like we do. It must have been very uncomfortable. A：We’ve discovered fireplaces in the center of the caves 66._____ they made fires. That would have kept them warm，cooked the food and scared wild beasts away as well. We have been excavating layers of ash almost six meters thick，which 67._____(suggest) that they might have kept the fire burning all winter. We haven’t found any doors but we think they might have 68._____(hang) animal skins at the cave mouth to keep out the cold 69._____ the freezing winter. S3：70._____ wild animals were there all that time ago? A：Well，we’ve been finding the bones of tigers and bears in the caves，and we think these were their most dangerous enemies. Now what do you think this tells us about the life of these early people?