Dadas as sentenças:
- Until scientists started talking about global warming, most people hadn’t known much about the damage their cars and industries were causing.
- When the price of gasoline becomes enough expensive, Brazilians can fill their cars with ethanol.
- In the next few years, we’ll have to come up with new sources of energy to replace the harmful ones we have now.
- Europeans has used coal as their primary source of energy until inventors and scientists found new solutions.
Assinale a alternativa que indica todas as afirmativas corretas.