機器
activity
big
career
coal
coalfield
construction
development
dig
digger
diging
dirt
dragline
dredger
earth
ecology
environment
equipment
excavate
excavator
exploration
gear
heavy
industrial
industry
large
limestone
machinery
metal
mine
mineral
mining
mover
open
ore
pit
quarry
resource
rock
site
sky
steel
stone
technology
work