Put the correct form of the words in brackets.
1. Coal is plentifulplentinentplentifully, but we still have to use it economically. (plenty)
2. The movement of waves and tides in the ocean can be able to generate electronicelectricityelectrical. (electric)
3. Scientists are looking for clean and affectineffectiveeffective sources of energy. (effect)
4. Non-renewable energy are not environmentalenvironmentalistenvironmentally friendly and can have detrimental effect on our health. (environment)
5. Natural gas is less pollutedpollutionpollutant than coal or crude oil. (pollute)
1 plentiful
2 electricity
3 effective
4 environmentally
5 polluted