若x2+mx+9是关于x的完全平方式，则m=（ ）．
±6
He to school by bike, but now he to school on foot.
A．used to going; gets used to go
B．used to go; gets used to go
C．used to go; gets used to going
在俄国高等教育史上最具影响的大学是（）大学。
