Ключевые слова: activity, blue, business, cement, cobblestone, concrete, construction, conveyor, crusher, dirt, dust, earth, environment, equipment, excavation, excavator, factory, gravel, heap, heavy, hydraulic, industrial, industry, loading, machine, manufacturing, material, mine, mineral, mining, operation, outdoors, pit, plant, pollution, processing, production, quarrel, quarry, rock, sand, sky, steel, technology, transport, work,