sentences: particles in a liquid are closer together than particles in a gas
docs: liquid has weaker_internal_forces_than_solid gases is more_compressible_than_liquids_or_solids. liquid_gas is gas. gas_escaping_from_liquid is separating_mixture. liquid is fluid. liquid_water is denser_than_air. gas has weaker_internal_forces_than_liquid liquid is liquid. liquid is not_gas. fresh_water_particle is particle.