若函数f（x）=$\left\{\begin{array}{c}-x+6,\le 2\\ 3+{\log }_{a}x,x>2\end{array}\right.$（a＞0且a≠1）的值域是4，+∞），则实数a的取值范围是____ 

读某地区图，回答下列问题。

清朝学者赵翼写诗说：“千秋疑案陈桥驿，一著黄袍便罢兵。”该诗讲的是哪位皇帝（　　）

阅读诗歌，回答问题。

                                                                                                                                       绝句

                                                                                                                                    (唐)杜甫

                                                                                                                    迟日江山丽，春风花草香。

                                                                                                                    泥融飞燕子，沙暖睡鸳鸯。

      【注释】泥融：指冻泥融化，又软又湿。