Question

 1. what / a / carbon / is / footprint

 2. oil / is / why / energy / source / non-renewable / a

 3. should / we / why / energy / save ?

 4. the countryside / a big city. / has / fewer problems / than

Answer 1

 1. what / a / carbon / is / footprint

→ What is a carbon footprint ?

 2. oil / is / why / energy / source / non-renewable / a

→ Why is oil a non-renewable source energy ?

 3. should / we / why / energy / save ?

→ Why should we save energy ?

 4. the countryside / a big city. / has / fewer problems / than

→ The countryside has fewer problems than a big city .

mình không chắc chắn lắm đâu vì phần sắp xếp câu mình còn rất yếu. :>