根据“be not supposed to do sth.不应该做某事”可知应用动词原形。 5. When Bob is upset or tired, he likes to listen to music that can ___. A. look it up B. clean them up C. cheer him up D. pick it up 【答案】C 【解析】考查动词短语辨析。句意:当鲍勃焦...