阅读下面的古诗，完成两小题。
                                                                                                                           《恨别》 杜甫
                                                                                                          洛城一别四千里，胡骑长驱五六年。
                                                                                                          草木变衰行剑外，兵戈阻绝老江边。
                                                                                                          思家步月清宵立，忆弟看云白日眠。
                                                                                                          闻道河阳近乘胜，司徒急为破幽燕。
      【注】河阳，地名。末句中“司徒”即指时任检校司徒的李光弼在此大败叛军后，又急欲直捣安史之乱叛军老巢幽燕，以打破相持局面。