单项选择题
The steam coils in a high pressure evaporator used for saltwater service should be de-scaled with （）.
A.a needle gun
B.soap and water
C.a wire brush
D.a chipping hammer
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相关考题
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单项选择题
Which of the listed chemicals can be routinely used to maintain the hygienic quality of potable water?（）
A.Hydrochloric acid
B.Chlorine
C.Sulfuric acid
D.Zinc chromate -
单项选择题
The ratio of the weight of moisture contained in a given volume of air, to the weight of moisture that the same sample would hold if saturated, is called the（）.
A.absolute humidity
B.relative humidity
C.specific humidity
D.total humidity -
单项选择题
If a centrifugal pump is driven by a constant speed electric motor and produces a discharge pressure less than designed, the cause is probably（）.
A.excessive pump speed
B.excessive suction head
C.worn wearing rings
D.gross pump misalignment
