阅读下面这首元曲，回答小题。
                                                                                                     天净沙 秋思
                                                                                                   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。