分动外锁闭道岔管理有何规定？
参考答案：
分动外锁闭道岔电务部门必须保证外锁闭装置完整，机械锁闭框清洁，锁闭作用良好。
Nowhere in nature is aluminum found free,owing to its always with other elements,most
commonly with oxygen. [ ]
A.combined
B.being combined
C.combine
D.having combined
往复泵压力波动大的原因及处理方法？
