The
source
is
the
____________________
____________________
of
the
river
.
Upper
course
is
the
____________________
stage
of
the
____________________
in
the
____________________
.
Middle
course
is
the
____________________
where
the
____________________
____________________
more
____________________
.
Lower
course
is
the
____________________
stage
and
____________________
flows
____________________
,
it
also
deposit
____________________
.
The
mouth
is
i
the
____________________
stage
and
the
____________________
____________________
by
the
river
____________________
into
another
____________________
.