These are the most frequently used words in this book.
1995
air
although
amount
animals
another
area
between
called
carbon
case
cause
cent
change
climate
conditions
countries
crops
different
dioxide
during
earth
effect
energy
environment
environmental
even
example
figure
first
food
forest
form
ground
habitat
high
however
human
ice
increase
individuals
known
land
large
less
level
london
long
material
may
means
might
million
must
natural
new
north
now
number
occur
oceans
often
organisms
part
people
per
places
plants
pollution
population
pp
present
process
produce
provide
rate
regions
remains
resources
river
rock
science
sea
section
small
soil
species
surface
system
temperature
time
trees
two
use
used
wastes
water
wind
world
years