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單項選擇題

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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單項選擇題

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

單項選擇題

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