如图，在△ABC中，BA=BC，以AB为直径的⊙O分别交AC，BC于点D，E，BC的延长线与⊙O的切线AF交于点F．

（1）求证：∠ABC=2∠CAF；

（2）若AC=2$\sqrt{10}$，CE：EB=1：4，求CE，AF的长．

雄安新区规划范围涉及河北省雄县、容城、安新三县及周边部分区域，地处北京、天津、保定腹地，区位优势明显，交通便捷通畅，生态环境优良，资源环境承载能力较强，现有开发程度较低，发展空间充裕。规划建设雄南新区的重点任务是：建设绿色智慧新城，建成国际一流、绿色、现代、智慧城市；打造优美生态环境，构建蓝绿交织、清新明亮、水城共融的生态城市；发展高端高新产业，积极吸纳和聚集创新要素资源，培育新功能；提供优质公共服务，建设优质公共设施，创建城市管理新样板；构建快速高效交通网，打造绿色交通体系；推进体制机制改革，发挥市场在资源配置中的决定性作用和更好发挥政府作用，激发市场活力；扩大全方位对外开放，开放创新高地和对外合作新平台。

结合材料，说明规划建设雄安新区对推动京津冀协同发展的经济意义。

短文改错

增加：在缺词处加一个漏词符号（ˆ）, 并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线, 并在该词下面写出修改后的词。

注意:1.每处错误及修改均仅限一词;2.只允许修改10处，多者（从第11处起）不计分

    Having a good teacher do mean a lot to us students and I am lucky enough to have the one ----Miss Brown, my English teacher.

    Miss Brown is a charming lady always worn a big smile on her face. In the first class she introduced her and then asked us to say something about ourselves with English. When it was my turn, I felt too shy and fearful that I didn't dare to say a word. She came up to me and said, “Don't afraid. You can make it. Just have a try.” At last, I did it quite good. She praised me for that I had done.

    Never shall I forgot my first English class in senior high school.

I ____ back my hometown for a couple of years. I miss it a lot.

建立自然保护区是保护生物多样性最为有效的措施．因为自然保护区是（  ）