Fish use their respiratory organs to take in oxygen underwater.

His irresponsible behavior caused an accident.

Mars refers to the planet Mars.

MERS is a virus that causes serious respiratory diseases.

He is suffering from a serious disease.

This problem is very serious.

Do you understand the seriousness of this problem?

Moderate exercise and a balanced diet are important for maintaining the health of the respiratory system.

He is connected to a ventilator due to his severe condition.

He took a deep breath and regained his composure.