如图，抛物线y=x²+bx+c与x轴交于A，B两点，与y轴交于C点，若∠OBC=45°，则下列各式成立的是（　　）

____

下列哪一史实不可能在《史记》中出现（    ）

    Now you are in a dinosaur ____park. Coming here, you will find a kind of old ____, dinosaur, which died out millions of years ago. In our park, we are happy to show you ____ dinosaurs, which lived in the Jurassic. The four-storied-building-high grass-eating dinosaurs are submissive (温顺的) and kind. You can ____ towards them and touch them. But the ____  of them are dangerous. The four-legged meat-eating dinosaurs are very cruel. Please don't ____ them and don't try to give them food. The ____ here is very thick and full of all kinds of animals that lived in the Jurassic. Without any special____and the leading of the guide, please don't step into it. OK, I'm sure that our park will ____anyone who comes here and you will ____a lot from it.

李老师带着三年级56名同学去公园划船，每条船限乘4人，至少需要（　　）条船？