機器
background
business
chemical
commerce
commercial
concept
economy
electricity
energy
engineering
environment
equipment
factory
field
foreground grass
fuel
gas
gasoline
grass field
green
industrial
industry
industry background
line
manufacture
manufacturing
metal
nature
oil
oilindustry
outdoor
petrochemical
petroleum
physical
pipe
pipeline
piping
plant
pollution
power
production
pump
refinery
sky
steel
technology
tower
transportation
tube