阅读古诗《泊秦淮》，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》。