When the engineer and his assistant jut their heads through open side windows to see the track ahead, coal cinders whip into their faces.Their bloodshot eyes tear.

• 不需信号，司机和他的助手把他们的头伸出开着的侧窗了望前方的路轨，煤炭灰打在他们的脸上，他们的眼睛透着血丝，流着泪水。