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As there is less and less coal and oil, scientists are exploring new ways of making use of ______ energy, such as sunlight, wind and water for power and fuel.

A. primary      B. alternative       C. instant          D. unique

As there is less and less coal and oil, scientists are exploring new ways of making use of ______ energy, such as sunlight, wind and water for power and fuel. 

A. primary      B. alternative       C. instant          D. unique 

6. As there is less and less coal and oil, scientists are exploring new ways of making use of    energy, such as sunlight, wind and water for power and fuel.

A. primary         B. alternative          C. instant         D. unique

As there is less and less coal and oil, scientists are exploring new ways of making use of ______ energy, such as sunlight, wind and water for power and fuel. 

A. primary      B. alternative       C. instant          D. unique 

As there is less and less coal and oil, scientists are exploring new ways of making use of ______ energy, such as sunlight, wind and water for power and fuel.

A. primary      B. alternative       C. instant          D. unique