We
can
____________________
animals
in
different
ways
.
For
example
,
according
to
the
type
of
____________________
they
eat
or
the
way
they
____________________
.
One
of
the
most
common
ways
to
classify
____________________
is
whether
or
not
they
have
an
internal
____________________
.
Through
this
method
,
animals
are
classified
as
____________________
and
invertebrate
.