Chalcolithic

例句：

1. 1. The Chalcolithic period is marked by the discovery of fire.
   石器时代以发现火为标志。
2. 2. The Chalcolithic tools found in the cave are evidence of human evolution.
   洞穴中发现的石器工具是人进化的证据。
3. 3. The Chalcolithic culture was characterized by its simple tools and lifestyle.
   旧石器时代的文化以其简单的工具和生活方式而著称。