预涂涂层应总是采用刷涂施工。

一个两位数，个位数字是n，十位数字是m，这个两位数可表示为______．

管道运输主要用于（）输送。

A．煤气和天然气

B．原油和天然气

C．水和天然气

D．水和沼气

“打造诚信中国”、“构建社会主义和谐社会”、“形成良好文化关系”反映的诚实守信的（）

A.经济价值

B.社会价值

C.道德价值

Alan, returning home very lately from his club, found an angry wife waiting for him.

What does blowing tubes accomplish?（）

A.Eliminates unburned fuel oil residues from the firebox

B.Increases boiler efficiency

C.Flushes away mineral deposits inside the water tubes

D.Cleans soot deposits from the inside of the stack