Bison

horse

bear

deer

fish

wolf

seal

polar bear

caribou

snowy owl

walrus

whale

artic fox

garbage dump

air pollution

muck

rainwater

toxic chemicals

smoke

endangered species

recycling bin

present = produce
past= produced

present = waste
past = wasted

present = dump
past = dumped

present = pollute
past = polluted

present = save
past = saved

present = change
past = changed

Present = Conserve
Past = Conserved

present = decide
past = decided

wooden house

railroad

factory

bridge

steel mill

research center

visitor's center

canoe

subway