1. Some towns in the United States have
   had to limit the number of wood-burning
   stoves for environmental reasons. What is
   the greatest problem caused by the use of
   wood-burning stoves?
   The manufacture of the stoves requires
   iron, which is a rare metal.
   The Heat from the stoves causes thermal
   pollution.
   The smoke from the stoves contributes
   to air pollution.
   The wood is a scarce fossil fuel.