一般来说,每门独立的学科都由三部分组成,即理论部分、应用部分和历史部分,没有理论等于没有灵魂;不应用于实践就会失去生命力;不注重总结经验,不了解自身发展史,就不能指导本学科不断发展。 机械工程从最简单的尖劈、杠杆、轮轴、螺旋 In general, each independent discipline consists of three parts, that is, the theoretical part, the applied part and the historical part. No theory equals no soul. Without applying it to practice, it will lose its vitality. It does not pay attention to summing up experiences and does not understand the history of its own development , Can not guide the continuous development of this discipline. Mechanical engineering from the simplest wedges, levers, axles, spirals