Bridges
are
an
important
invention
;
they
____________________
places
and
people
.
A
bridge
can
be
built
over
a
____________________
,
a
stream
,
a
valley
,
a
canyon
,
a
road
etc
.
It
can
be
made
of
____________________
,
stone
,
brick
or
iron
.
Today
we
usually
build
bridges
using
concrete
and
steel
.
Building
bridges
is
not
an
____________________
job
.
The
first
bridges
were
made
of
tree
trunks
or
stones
.
In
South
____________________
,
the
Inca
people
made
rope
bridges
.
Those
were
a
simple
type
of
today's
bridges
.
The
real
time
for
bridges
was
the
19th
century
,
when
people
started
using
steel
and
concrete
,
so
they
could
make
____________________
bridges
.
