英文關鍵字
brown
corrode
corrosion
dam
drain
drops
ecology
environment
fall
flood
flow
flowing
fluid
fold
hole
industrial
industry
jet
junk
large
liquid
metal
motion
movement
natural
parallel
pile
pipe
pipeline
piping
pollution
pumping
pure
reinforced
relief
round
run
rust
rusted
rusty
stack
steel
straight
stream
technology
tube
waste
water
waterfall