sentences: as the roughness of something cars , the slip of that something will increase
docs: roughness is texture. cars is one_kind_of_thing. bumpiness is roughness. gravity has effect_of_pulling_things_down cars_and_autos is words_with_same_meaning. fast_car is single. fuel_rearrangement is dispersion_of_stuff. abruptness is gradient. traffic_jam is traffic. cars is things.