add

adjust

appliance

background

blur

clean

condition

electric

energy

environment

equipment

farm

fill

float

flow

generator

green

lake

machine

metal

motion

motor

nature

oxygen

plant

pollution

pond

pool

power

pump

purify

recycle

revolve

river

run

spin

spinning

supply

surface

swamp

system

technology

tool

treat

treatment

tree

turbine

twirl

utility

water

well

wheel

whirl

work