英文關鍵字
canal
chemical
concrete
danger
dirty
ecology
environment
factory
garbage
harm
industry
pipe
pollution
problems
river
sewage
sewer
technology
toxic
tube
urban
waste
water
英文關鍵字
canal
chemical
concrete
danger
dirty
ecology
environment
factory
garbage
harm
industry
pipe
pollution
problems
river
sewage
sewer
technology
toxic
tube
urban
waste
water