sentences: a potassium is a mean of preposition
docs: potassium_bromide is salt. potassium_phosphate is salt. atelic_directional_preposition is spatial_preposition. preposition_of is preposition. potassium_32 is potassium. locative_preposition is spatial_preposition. directional_preposition is spatial_preposition. spatial_preposition is preposition. preposition is function_word. telic_directional_preposition is spatial_preposition.