機器
macadam
abstracts
apocalypse
armageddon
automated
automatic
background
breakstone
business
cement
clouds
cobblestone
concrete
construction
conveyor
crusher
crushing
danger
dirty
disaster
dredge
dust
ecology
efficiency
environment
equipment
excavation
factory
global
gravel
haze
heavy
hell
industrial
industry
landscape
machinery
manufacturing
mine
motion
nature
order
outdoors
plant
polluted
pollution
problems
production
quarry
robot
rock
row
sky
smog
smoke
stone
technology
tool
warming
work
working