燃气管道穿越铁路时应加套管套管内径应比燃气管道外径大( )以上。
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A.50mm
A.50mm
B.70mm
B.70mm
C.100mm
C.100mm
D.150mm
D.150mm
参考答案:
A.50mm
A.50mm
B.70mm
B.70mm
C.100mm
C.100mm
D.150mm
D.150mm
参考答案: