trackbed道床trackn.轨道；跑道；踪迹；小路；乐曲v.追踪；跟踪track laying vehicle铺轨车track reconstruction线路改建track oiling machine轨道上油机track-hold circuit跟踪保持电路tracker registration跟踪注册track laying machine铺轨机track carrier roller链轨托轮track circuit length轨道电路长度tracking file system追踪文件系统track average method径迹平均方法