英文關鍵字
pollution
industry
dirty
river
sewage
water
environment
danger
pipe
factory
nature
industrial
stream
liquid
waste
garbage
flowing
ecology
sewer
toxic
unhygienic
outdoor
environmental
drain
pipeline
discharge
tube
background
dump
technology
drainage
flow
energy
old
chemical
treatment
waterfall
canal
rusty
wastewater
disaster
urban
corrosion
problem
natural
metal
system
effluent
plant
warming