sentences: if a substance has a higher density than another substance , then the molecules in the substance will be closer than those of the other substance
docs: metals is stronger_than_others. density is multi_dimensional_quantity. substance is substance. epidermal_growth_factor_molecule is epidermal_growth_factor. growth_factor_molecule is cellular_growth_factor. epidermal_growth_factor_molecule is growth_factor_molecule. proliferation is increase. metals is weaker_than_others. density is tangible_physical_quantity. cellular_growth_factor is molecular_material.