单项选择题
A.water-tube B.fire-tube C.exhaust gas D.none of the above
The tube in a boiler should be blinded if found （）.A.sc...
单项选择题The tube in a boiler should be blinded if found （）.
A.scaled B.informed C.leaky D.deformed
The internal part of boiler should be welded by yard if...
单项选择题The internal part of boiler should be welded by yard if found （）.
A.sealed B.cracked C.shape changed D.deformed
The internal part of the boiler, if found （）, has to be...
单项选择题The internal part of the boiler, if found （）, has to be chemically washed by yard.
A.deformed B.rusted C.cracked D.scaled
