阅读下面一首诗，完成后面题目。
                                                                                             望洞庭湖赠张丞相
                                                                                                       孟浩然
                                                                                        八月湖水平，涵虚混太清。
                                                                                        气蒸云梦泽，波撼岳阳城。
                                                                                        欲济无舟楫，端居耻圣明。
                                                                                        坐观垂钓者，徒有羡鱼情。