Compléter Text energyVersion en ligne Fill in the gaps, choose the correct answer par Анна Пак 1 great solar cause hydro important This problem is very . 2 work cause free energy important The sun is a source of energy . 3 use free use work popular People coal to produce electricity . 4 work coal cause change panel Solar panels best in sunny places . 5 change work important use cause Wind turbines wind energy into electrical power . 6 solar cause power plant free Wind turbines no pollution .