The following text is for questions number 1819
to 19.
Some of the world's finest roads make
use of bodies of water. They are called canals.
Canals are man made waterways. They are
usually straight and narrow. But they are filled
Th
with water. They connect rivers and lakes,
to
oceans and lakes, rivers and rivers, and
oceans and oceans so that boats and ships
can go from one to the other.
Most canals are used for transportation
Barges, boats, and ships carry goods over
canals. Some are used to irrigate land or to
carry sewage from large cities. Canals also
reduce the cost of shipping goods and offer
travel short cuts.
Canals even go over hills and mountains.
But you know that water can't flow up a hill;
so how can the water and boats in a canal go
up a hill? Something called a lock is used. It
is a giant tank. The tank is big enough to hold
a long boat. The boat floats into the tank, and
the doors behind it are closed to lock the boat
in there. Then more water is let into the tank.
When the tank is full of water, the tank door in
front of the boat is opened and the boat floats
out. The boat floats higher and higher as the
water rises. It floats either out into a higher
part of the canal or into another tank or lock,
which will lift it still higher.
To go down the hill on the other side, the
boat enters a lock that is full of water. As the
water is let out of the lock, the boat will float
lower and lower. So locks make it possible for
boats or ships to move from one water level
to another.

jawablah pertanyaan di foto
dan ini 19. we know from the text that a lock is​