阅读下面的古诗，完成后面问题。
                                                                                                   泊秦淮
                                                                                                     杜牧
                                                                                烟笼寒水月笼沙，夜泊秦淮近酒家。
                                                                                商女不知亡国恨，隔江犹唱《后庭花》。