Give the correct form of the word given to complete the sentences. 1. Tidal energy is renewable, ____________and clean. (plenty) 2. Wind will be used as an ____________friendly sources of energy. (environment) 3. There are many ways will be used to solve the problem of _____________. (pollute) 4. Solar power can be used to ____________or cool our houses. (hot) 5. _______________, fossil fuels are harmful to the environment. (fortunate) 6. We should use them_________ and try to find out alternative sources of power. (economy) 7. Solar energy is____________, plentiful and clean. (renew) 8. I think that solar energy can be an___________ source of energy in the near future. (alter) 9. We should reduce the use of___________ at home. (electrical) 10. It’s a clean source of energy. Sailboats couldn’t move without this________. (powerful)