He is an expert in chemistry.

He received the letter challenging him to a duel and began preparing for the duel.

This dish is too salty.

This dish is too low on salt.

This dish is too low on salt.

The citric acid cycle plays a crucial role in the energy production of cells.

Gender roles are an important element in defining individual behavior in society.

His role is to fulfill his responsibilities as a leader.

It is important to understand the importance of health.

Organic solvents play an important role in chemical reactions.