• Kekule made his classical proposal that the six carbon atoms of benzene were arranged in a hexagon.
• It has been proposed ( or speculated , or suggested ) that a series of reactions is involved.
• He suggested that there should be two gas diffusion terms.
• Goldbach conjectured that every even number ...
• He proposed that both attractive and repulsive forces could exist between atoms.
• It is speculated that the oxygen resulted from the bombardment of the seas by certain wavelengths of ultraviolet light.
• Scientists theorize that the planets in our solar system formed at ...
• It was conjectured that the eukaryotes had eliminated the need for ... ( биол. ).
• The suggestion has been made that the underlying asthenosphere has an undulating upper surface.
• He reasoned ( or argued , or hypothesized ) that erosion must be burying layers of sediment under ...