sentences: red blood cells are a part of blood
docs: blood_group is blood. blood has red_blood_cells_white_blood_cells_platelets_and_plasma blood is red. sickle_cell is red_blood_cell. blood is body_part. mammalian_red_blood_cell is rbc. red_blood_cell is blood_cell. blood_cell is animal_or_body_part. blood_sample is blood.