When playing football, Tom had his leg b____and was sent to a hospital.
写出下列各词的反义词。
容易— ____ 消失— ____
甲、乙两个完全相同的篮球，在同一水平面上以大小相等的速度，同时将甲球竖直向上抛出、将乙球水平方向抛出，两球在地面上反复弹跳。运动中不计空气阻力，与地面碰撞 时不计能量损失。则下列说法错误的是（ ）
