ruthless

a.无情的；残忍的

russet, Russia, Russian, Russian roulette, Russo-, rust, rust-proof, rustic, rustically, rusticate, rustication, rusticity, rustily, rustiness, rustle, rustler, rustling, rusty, rut, rutabaga, ruthlessly, ruthlessness, rye, S, S, s, S-bend, s. s., SA, Sabbatarian, sabbath, sabbatical, sable, sabot, sabotage, saboteur, sabra, sabre (US saber), sabre-rattling, sabre-toothed, sabre-toothed tiger,