big
brown
bucket
coal
color
countryside
diesel
dig
dragline
dredging
electricity
energy
engine
environment
equipment
gear
giant
ground
heap
heavy
hoe
hydraulic
industrial
industry
landscape
large
machinery
mining
nature
open
part
pile
pit
plant
pollution
power
protection
quarries
sand
scoop
shovel
site
sky
steel
territory
trace
transportation
work
yellow activity