Completa la oración pasiva con la forma correcta del verbo.

The greenhouse effect causes serious climate changes
serious climate changes___________ by the greenhouse effect


Leo Dicaprio listed several environmental issues in his Earth Day speech
Several environmental issues________________ by Leo Dicaprio in his Earth Day


Some famers are overusing chemicals in their crops
Chemicals____________ by some farmers in their crops

Deforestation has destroyed some rainforest ecosystems
Some rainforest ecosystems_____________by deforestation