停止作业并己撤除通风设备而又无贯穿风流通风的采场、独头上山或较长的独头巷道，应设栅栏和警示标志，防止人员进入。
参考答案：对
Bill is not a fast runner and he doesn't have a chance of winning the marathon, but he will _____ the race even if he finishes last.
A．keep on
B．keep to
C．stick out
D．stick to
简要说明软交换设备的主要数据。
