空气阻尼器

air borne

bunker door (air-raid shelter door)

air drain【建】;air duct【建】矿业;vent gutter【建】矿业

air velocity through grain mass【粮食】

secondary air (supplementary air) detoxication of exhaust gases

Filter-type Air Extractor

oxygen-enriched air roasting【冶】

secondary air register