音乐____    科学____

下午____   subject____

timetable____

已知O为△ABC所在平面内一点，且满足$\overrightarrow{OA}$²+$\overrightarrow{BC}$²=$\overrightarrow{OB}$²+$\overrightarrow{CA}$²=$\overrightarrow{OC}$²+$\overrightarrow{AB}$²，则O点的轨迹一定通过△ABC的（　　）

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    My name is Sally. There are 1 people in my family. My grandfather 2Mike. His birthday is 3 February 7th. My 4 name is Alan. August 5 is his birthday. My grandmother is Jane. 6 birthday is on April 8th. My mother's name is Jenny. Her birthday is 7 September. Do you know(知道) 8 my birthday is? Oh, 9 on November 26. I like to go mountain 10 on that day.