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Michelle Cha Posted 12 years ago
Grammar

Newly developed methods are challenging fossil fuels.

"Newly developed methods are challenging fossil fuels."

I don't understand the meaning of this sentence. - especially 'challenging'.

Please help me out.
  

Top answer

New methods of using the fuels in more efficient ways—how efficiently can fossil fuels be used?

  • New methods of using the fuels in more efficient ways—how efficiently can fossil fuels be used?
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1 Answers
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New methods of using the fuels in more efficient ways—how efficiently can fossil fuels be used?

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