由名词“所”和动词“以”演变虚化、凝结成固定结构“所以”，在先秦作品中的类型、意义和用法；先秦时期的介词结构“所以”发展到现代汉语里用作连词的演变原因和过程，以及“所以”用作介词结构和用作连词的区别。 It is a combination of the nouns “所所” and the verb “以” evacuation, and condenses into the fixed structure “So”, the type, meaning and usage in the pre-qin works. The preposition structure of “Pre-Qin period” therefore developed into modern Chinese and used as conjunctions The causes and processes of evolution, and the “so” are used as a prepositional structure and as the difference between conjunctions.