black
blue
business
businessman
chemical
construction
crane
diesel
dirty
drip
drop
ecology
energy
engineer
engineering
environment
environmental
equipment
factory
flow
flowing
fuel
gas
gasoline
industrial
industry
isolated
joy
labor
liquid
male
man
metal
natural
oil
people
petrochemical
petrol
petroleum
pipe
pipeline
plant
pollution
power
production
professional
pump
refinery
resource
sewage
steel
stream
strip
success
technology
tube
unlock
valve
water
work
worker