_____ he lives alone, he doesn't feel lonely. [ ]
A. If
B. Because
C. When
D. Although
答案:D
沿铁道线路行走时,应在()或路旁走行。
曲线区段承力索位置限界值为()。
A、±50mm
B、±200mm
C、允许向曲线内侧偏移150mm
D、允许向曲线外侧偏移150mm