The ejecta from the volcano plays an important role in shaping the terrain.

He refused to clean up the vomit.

This mineral is very rare.

My favorite bowl dish is Oyakodon.

Nitrogen monoxide is a cause of air pollution.

Nitrogen dioxide is a cause of air pollution.

Carbon monoxide is a colorless, odorless gas, and it is dangerous to inhale.

Carbon dioxide is one of the main causes of global warming.

This factory is emitting a large amount of sulfur dioxide.

Hydrogen peroxide is often used for disinfecting wounds.