機器
background
belt
coal
construction
conveyor
dig
digging
dirt
dust
earth
ecology
engineering
environment
equipment
erosion
factory
fossil
fuel
gravel
heavy
industrial
industry
iron
landscape
large
machinery
material
metal
mine
mineral
mining
natural
nature
ore
pit
quarry
rock
sand
sky
stack
stone
technology
transport
transportation
truck
vehicle
waste
work
yellow