Exercise 6: Read the passage and fill in the blanks with the most suitable answers: There (23) __ three major forms of fossil fuels: coal, oil, and natural gas. All three were (24) __ many hundreds of millions of years ago before the time of the dinosaurs (25) __ we call them fossil fuels. Fossil fuels take millions of years to make. (26) __, they are not unlimited. We are using up the fuels that were made more than 300 million years ago. (27) __ they are not renewable like solar power, wind power, hydro power, or biogas, we can save them by reducing the amount we consume.

Exercise 6: Read the passage and fill in the blanks with the most suitable answers: There (23) __ three major forms