求翻译：介绍了目前地铁常用的三种车门结构：内藏门、塞拉门、外挂门，并分别分析了各类车门结构的优缺点。通过近年来常发生的地铁车门故障，总结了导致车门故障的各类因素（主、次要因素和客观因素）并提出相对应的改善和解决措施。目前车门结构在密封性、安全性等方面还存在待解决和改善的问题，这在一定程度上阻碍了地铁车速的提高和舒适度的提高，但目前很多研究正致力于解决这些问题。是什么意思？

Describes the current structure of the MTR used three doors: built door, plug door, plug door, and were analyzed the structure of the advantages and disadvantages of various types of doors. In recent years, often occurs through the fault of the subway doors, summed up the failure of the various fact

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Describes the current Metro commonly used three-door structure: inside doors, sailamen, hack, and individually analyzes the advantages and disadvantages of various types of door structure. Subway door failure that occurred through has been, summarized result in door failures of various factors (main

Describes the current structure of the MTR used three doors: built door, plug door, plug door, and were analyzed the structure of the advantages and disadvantages of various types of doors. In recent years, often occurs through the fault of the subway doors, summed up the failure of the various fact