英文關鍵字
canal
chemical
concrete
corrosion
danger
dirty
drainage
dump
ecology
energy
environment
factory
flow
flowing
from
garbage
global
industrial
industry
liquid
natural
nature
old
outdoors
pipe
pipeline
polluted
pollution
pouring
river
rusty
sewage
sewer
stream
substance
technology
toxic
treatment
tube
urban
waste
water