单项选择题
A.filter B.hole C.pollution D.content
The internal part of boiler should be cleaned by yard i...
单项选择题The internal part of boiler should be cleaned by yard if found （）.
A.scaled B.worn C.deformed D.rested
At normal sea going, we use （） instead of donkey boiler...
单项选择题At normal sea going, we use （） instead of donkey boiler.
A.a heater B.a pre-heater C.an exhaust gas boiler D.the coal burning boiler
The soot blowers are operating in the oil fuel boiler t...
单项选择题The soot blowers are operating in the oil fuel boiler the air/fuel ratio must （） throughout the action, and blowers greased after use.
A.be increased B.be decreased C.remain constant D.either be increased or remain constant
