英文關鍵字
background
belt
bituminous
black
carbon
charcoal
clay
coal
conveyor
danger
digging
dirt
dust
ecology
energy
engine
environment
equipment
extraction
factory
flammable
fossil
fuel
heating
industrial
industry
land
lignite
loader
loading
machine
machinery
man
manufacturing
metallurgy
mineral
mining
moving
outdoor
pile
pollution
power
processes
production
reserve
resource
roller
skid
soap
steer
stone
technology
texture
vehicle