请你阅读古诗，完成后面的题。
                                                                                                              夜雨寄北
                                                                                                               李商隐
                                                                                     君问归期未有期，巴山夜雨涨秋池。
                                                                                     何当共剪西窗烛，却话巴山夜雨时。