Three avenues that must be followed are: Switch to renewable energy sources: sound alternatives to coal, oil and gas already exist: solar energy, wind energy, alternative fuels for engines, hydro-electricity, biomass energy (the burning of sustainable natural fuels);
(Three avenues; must be followed; ) (Three avenues that must be followed; are; sound alternatives to coal, oil and gas already exist) (sound alternatives to coal; exist; T:already)
Three avenues Three avenues that must be followed sound alternatives to coal
must be followed are exist
sound alternatives to coal, oil and gas already exist
T:already