People often say that a dog is man's best friend. Over thousands of years,
man has taught his dogs to do many kinds of work besides guarding the
home.
For
example,
sheepdogs
are
famous
for
their
ability
to
control
a
flock of hundreds of sheep.
Dogs
have been used
to
aid disabled people
for
centuries.
A
guide
dog
can lead its blind owner. Nowadays, dogs can be taught to turn on light
switches, open refrigerator doors and dial the telephone for their disabled
owners.
For
the
majority
of
people,
however,
dogs
are
simply
pets
and
friends for both young and old members of the family.