Fossil fuels used in transportation can cause problems. Which is a possible solution to these problems?
When an item is _____________it is made into a new product.
Which is not a source of renewable energy?
What percentage of the energy resources used by Americans comes from fossil fuels?

Burning oil as fuel can release harmful substances called________________.
Our society uses up vast amounts of nonrenewable sources of energy. What should we do
about energy sources in the future?
The overuse of fossil fuels leads to _____________.