题目

书面表达，回忆一下你的一次完美的假期生活，用英文向大家介绍一下你是怎样度过的。 答案：【答案】例文：Last summer, I went to Beijing with my father and mother. We went there by plane. And we stayed in Beijing for a week. We climbed the Great Wall. We were very tired, but the Great Wall was very great. We also visited the Tiantan and the Palace Museum. They were very amaming. We went to Wangfujing and went shopping too. It was crowded. We were very happy in Beijing.【解析】12．如图1，在△ABC中，AB=AC，点E是BC上一点，点D是AE上一点，且∠BDE=∠BAC，CF∥BD，交AE的延长线于点F．（1）探究线段AD与CF的数量关系．（2）若将“AB=AC，点E是BC上一点，点D是AE上一点”改为“AB=kAC，点E是BC延长线上一点，点D是EA延长线上一点”，其他条件不变，如图2，若AD=n，AF=m，∠BAC=α，求BD的长（用含m，n，k，α的式子表示）