sentences: a branch feet oxygen dioxide, water, and shadow into snow
docs: treading_water is aquatic_body_movement. snow is two_feet_deep. snow is crystalline_form_of_solid_water. oxygen is invisible_gas. air has oxygen_nitrogen_and_carbon_dioxide branch_water is water. dead_tree_branch is organic_matter. foot is vertebrate_foot. limb is branch. stomping_ground is ground.