The vertical and horizontal motions of a projectile can be treated independently . 抛射体的竖直方向和水平方向的运动能够分开来处理。
2.
At what precise moment will the moon be in the most favourable position to be reached by the projectile ? 月球在什么时候出现在抛射体最容易击中的位置上？
3.
Projectiles became more important because cannons could now fire balls over hundreds or yards . 抛射体变得更加重要，因为人们已能用大炮把炮弹射到几百码的距离之外。
4.
Other eyewitnesses depose that they - observed an incandescent object of enormous proportions hurtling through the atmosphere at a terrifying velocity in a trajectory directed south west by west 其他目击者还作证说，他们瞥见一颗发白热光的庞然大物，以骇人的速度沿着抛射体的轨道朝西南偏西方向腾空而去。
