There is a set of gear train models in the laboratory, which was bought from abroad at a high price. 试验室里有一套轮系模型，是从国外高价买来的。
A description was carried out on the complicated epicyclic gear train by adopting the functional schematic diagram and the knowledge of graph theory. 摘要采用功能示意图和图论知识对复杂周转轮系进行描述。
