Read the passage and choose the best answer.

There is now increasing concern about the world’s energy (23)____ , particularly about those involving fossil (24) ____. In less than a hundred years we shall probably exhaust all the present (25) ____ of oil and gas. The world’s coal (26) ____ should last langer but, once used, these cannot be renewed. It is important; therefore, that we should develop such (27) ____ sources of energy as solar energy as well as water and wind power.

Read the passage and choose the best answer.

There is now increasing concern about the world’s energy (23)____ ,