单项选择题
Personnel working with refrigeration systems, and subject to the exposure of refrigerants should wear （）.
A.face shield
B.a respirator
C.rubber gloves
D.an all purpose gas mask
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相关考题
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单项选择题
To absorb the wear resulting from impeller rotation and abrasives in the liquid, a centrifugal pump is usually fitted with （）.
A.lantern rings
B.bearings
C.easing volutes
D.wearing rings -
单项选择题
If the capacity of a centrifugal pump decreases gradually over a long period of time, you should replace the （）.
A.packing gland
B.mechanical seals
C.lantern rings
D.wearing rings -
单项选择题
Distilled water from an evaporator may be discharged into a potable water tank （）.
A.through a detachable hose connection
B.after passing through an activated charcoal filter
C.after chemical analysis shows it is fit for consumption
D.through a solenoid operated three-way valve
