黄河近几年没有出现断流，原因是（   ）

诗歌赏析
                                                                                                 次北固山下
                                                                                                     王湾
                                                                                      客路青山外，行舟绿水前。
                                                                                      潮平两岸阔，风正一帆悬。
                                                                                      海日生残夜，江春入旧年。
                                                                                      乡书何处达? 归雁洛阳边。