Houses
in
northern
parts
of
the
____________________
often
have
roofs
with
steep
slopes
.
It
is
easier
to
build
house
with
____________________
roofs
.
But
flat
roofs
cause
____________________
in
winter
.
Snow
can
pile
up
thickly
on
flat
roofs
.
It
cannot
be
removed
until
it
____________________
.
If
more
snow
falls
,
it
just
sits
on
the
flat
roof
.
If
snow
on
the
roof
,
it
can
cause
a
lot
of
damage
.
The
thick
snow
can
split
the
roof
____________________
of
houses
with
flat
roofs
.
But
snow
slides
off
steep
sloping
roofs
and
causes
____________________
damage
.
