a train of gears.的用法和樣例：
例句
- There is a set of gear train models in the laboratory, which was bought from abroad at a high price.
試驗室里有一套輪系模型，是從國外高價買來的。 - A description was carried out on the complicated epicyclic gear train by adopting the functional schematic diagram and the knowledge of graph theory.
摘要採用功能示意圖和圖論知識對複雜周轉輪系進行描述。
