official rules that say what people are allowed and not allowed to do
laws
change from solid to liquid (e.g. from ice to water)
melt
a large amount of water covering an area that is usually dry
flood
not existing any more
extinct
things that make water, air, and the ground unclean
pollution
material that people throw away
waste
a mixture of smoke, gases, and chemicals, especially in cities, that makes the atmosphere difficult to breathe and harmful for health
smog
the process of collecting and changing old paper, glass, plastic, etc. so that it can be used again
recycling
waste material or things that are no longer wanted or needed
rubbish
