sentences: neutrons are a kind of subatomic particle
docs: neutron_star_matter is neutronium. subatomic_particle is natural_inanimate_thing. beta_particle is particle. neutronium is neutron_matter. neutrons has spin alpha_particle is subatomic_particle. fast_neutron is neutron. subatomic_particle is microscopic_object. beta_particle is subatomic_particle. subatomic_particle is spatial_thing.