Fossil fuels & greenhouse gases Fossil fuels are energy sources that are naturally found in the earth's crust.
(Fossil fuels & greenhouse gases Fossil fuels; are; energy sources that are naturally found in the earth's crust) (energy sources; are naturally found; L:in the earth's crust)
Fossil fuels & greenhouse gases Fossil fuels energy sources
are are naturally found
energy sources that are naturally found in the earth's crust
L:in the earth's crust