请欣赏下面一首元曲，回答问题。

                                                                                                                           天净沙•秋思

                                                                                                                                马致远

                                                                                                              枯藤老树昏鸦，小桥流水人家，

                                                                                                             古道西风瘦马。夕阳西下，断肠人在天涯