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單項選擇題

A compressor should never be stopped （）.

A.without first cooling it
B.without first heating it
C.without first unloading it
D.without first loading it

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單項選擇題

Some （） lying in the starting air lines will give rise to corrosion and can cause water hammer.

A.air
B.moisture
C.cooling water
D.lubricant

單項選擇題

During compressors running the accumulated moisture in the separators must be （）.

A.drained off
B.collected
C.sent to the crankcases
D.separated with oil