轨道

track（电车）;rail（铁路）;orbit（卫星）;parabolic orbit（抛物线）;trajectory(射体、弹道)
火车出了～。The train has been derailed./五年计划上～。The Five-Year Plan is well under way./生产已走上～。Production has got on the right track./把卫星送入～put a satellite into orbit/绕月～ lunar orbit/双～double track; two-track/～车motor-trolley /～空间站orbital space station