sentences: fix down extract static from a part into materials
docs: grinding is material_handling. digging_up_root is removal_by_moving. static_friction is friction_vector. grinding is friction. removing_from_stuff is removal_by_moving. statics is mechanics. drill_bit is cutting_implement. spreading_stuff_onto_surface is applying_stuff_to_surface. find_downstairs is fuse_box. static_friction is surface_force_vector.