The four main systems of the Earth are
Ageology, meteorology, oceanography, and chemistry.
Bgeosphere, atmosphere, hydrosphere, and biosphere.
Caromatherapy, biology, chemistry, and physical properties.
Dgeosphere, atmosphere, hydrosphere, and aerosphere.
Ageology, meteorology, oceanography, and chemistry.
Bgeosphere, atmosphere, hydrosphere, and biosphere.
Caromatherapy, biology, chemistry, and physical properties.
Dgeosphere, atmosphere, hydrosphere, and aerosphere.