数学老师用粉笔在黑板上画了一条完美的抛物线。

The math teacher drew a perfect ___parabola on the blackboard with chalk.

在物理课上，我们学习了抛物线可以用来描述抛体运动的轨迹。

In physics class, we learned that ___parabolas can describe the trajectory of projectile motion.