如图为某班举行世界著名思想人物的主题班会所搜集的材料，最有可能涉及到下列哪一历史事件（    ）

根据短文内容判断句子正（T）误(F)。
Welcome to our school. Our school is on Xianyang Street. It’s next to the Xinhua Library. There is a big garden across from our school. The payphone is between our school and the post office. There are three buildings in our school, the students' building, the teachers'building and a library. The teachers in our school are good. Our school yard is very beautiful. If you come to our school from the airport, take a taxi and go along the highway until you see a bridge. Go across the bridge and turn left. Then go straight along the Bridge Street. Our school is on the right. 

当三角板绕点C旋转到CD与OA垂直时(如图①)，易证：OD＋OE＝ $\sqrt{2}$ OC；

当三角板绕点C旋转到CD与OA不垂直时，即在图②，图③这两种情况下，上述结论是否仍然成立？若成立，请给予证明；若不成立，线段OD，OE，OC之间又有怎样的数量关系？请写出你的猜想，不需证明．