阅读下面一首宋诗，然后回答问题。
                                                                                                       江上
                                                                                                    宋 王安石
                                                                                    江北秋阴一半开，晚云含雨却低徊。
                                                                                     青山缭绕疑无路，忽见千帆隐映来。