A. water-lubricated
B. oil lubrication
C. no lubrication
D. Lubrication with special lubricants
Answer: D
Analysis: Oil-free air compressors usually use special lubricants to cool and lubricate parts to ensure the purity of the compressed air.
A. General Standard B. Medical Standard C. Industry Standard D. No standard answer required: B. medical standard
A. Spraying and sandblasting operations B. Home use of C. Commercial places use D. Agricultural production uses answer: A. Spraying and sandblasting operations
A. Produce lubricating oil B. No lubricating oil C. Need to replace lubricating oil frequently D. High noise answer: B. No production of lubricating oil
A. Monthly B. Quarterly C. Once a year D. The answer depends on usage: D. Depending on usage
A. Backwardness of energy-saving technology B. Advanced energy-saving technology C. Don’t pay attention to energy-saving technologies D. General answer to energy-saving technology: B. Advanced energy-saving technology