There were vast differences between the instruments of production man used, his mastery of scientific knowledge, and his production experience and skills in the Stone, Bronze and Iron Ages and in the 17th, 18th and 19th centuries.

• 石器时代，青铜器时代，铁器时代，十七世纪，十八世纪，十九世纪，人们使用的生产工具，掌握的科学知识、生产经验和劳动技能，都大不相同。