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