The ejecta from volcanoes help to elucidate the geological history of the Earth.

This structure has existed for centuries.

He is an expert in mineralogy.

He is an expert in paleontology and is researching dinosaurs.

He is an expert in nuclear physics.

Bioweapons are a major threat to humanity.

In this experiment, we will observe the reaction of organic compounds.

In this experiment, we will use various inorganic compounds.

He always keeps in mind the phrase 'If one learns without thinking, it is a waste.'

When you exercise, your body releases endorphins, making you feel good.