阅读下面这首古诗，回答两题。
                                                                                                                    谢亭送别
                                                                                                                      许浑
                                                                                                              劳歌一曲解行舟，
                                                                                                              红叶青山水急流。
                                                                                                              日暮酒醒人已远，
                                                                                                              满天风雨下西楼。
       【注】①劳歌：送别歌。